NEW YORK (CNN/Money) - One sign that retailers were feeling good about their sales performance in April was the noted absence of the "gas prices are hurting our customers" excuse that merchants have been using month after month when results are below par.

"Instead of hearing about gas woes, we actually saw a handful of companies raise their earnings estimates. That was a nice surprise," said Ken Perkins, retail analyst and president of research firm Retail Metrics.

Among them was department store chain J.C. Penney (Research), which posted an increase in same-store sales -- or sales at its stores open at least a year -- of 3.6 percent last month. The retailer had expected sales to be flat to slightly up.

Based on April sales performance, Penney said it expects a first-quarter profit of 61 cents a share. Analysts currently expect the company to earn 52 cents for the quarter, according to earnings tracker Thomson Financial.

Federated Department Stores (Research) was another winner last month. The owner of Macy's and Bloomingdales posted a sales increase of 2.8 percent, trumping analysts' forecast for a 0.5 percent increase.

Federated raised its first-quarter forecast, saying that it now expects to earn 65 to 70 cents for the period, up from its earlier estimate of 45 to 50 cents a share profit.

Federated agreed to buy rival May Department Stores (Research) in an $11 billion deal in February. May's sales rose 1.5 percent.

Teen retailers and luxury sellers continued to roll on with impressive sales performances.

Sales jumped 16 percent at Abercrombie & Fitch (Research), 20 percent at American Eagle Outfitters (Research) and a whopping 31.2 percent at bebe (Research). High-end players Nordstrom (Research) saw sales rise 6.9 percent and Neiman Marcus (Research) was up 14.2 percent. Neiman Marcus this week announced that it had agreed to sell the company to a pair of private equity firms.

However, not everybody came to the party.

Wal-Mart, the world's largest retailer, said same-store sales grew 0.9 percent in April, in line with its earlier guidance.

Bentonville, Ark.-based Wal-Mart's net sales in the four-week period ended April 29 were $22.3 billion, up 7.4 percent over the same period a year earlier.

Sales at Wal-Mart (Research) discount stores rose 0.1 percent last month, while sales at its Sam's Club division rose a stronger 4.9 percent. Wal-Mart's initial projection was for total same-store sales to be up no more than 2 percent.

Analysts has expected the retailer's sales to rise 1 percent last month, according to First Call.

In a pre-recorded sales call, Wal-Mart said food sales outpaced sales of general merchandise in April.

Robert Brusca, chief economist with FAO Economics, said slowing sales at the discount behemoth could signal two things: Fluctuating gas prices hitting its core consumers and competitors starting to catch up.

Wal-Mart executives have repeatedly talked of higher gas prices as a continuing concern for the company.

"With a truck fleet as large as ours, higher fuel prices increase our transportation costs," Tom Schoewe, Wal-Mart's chief financial officer, told reporters last month. "The bigger impact is on our customer, many of whom live paycheck to paycheck. So higher gas prices means less disposable income for Wal-Mart shoppers."

"The fact that food sales outperformed other product categories last month is part of what's going on with the economy and its impact on consumers," Brusca said. "Also, there was a time when Wal-Mart was eating everyone's lunch. Other stores have been getting their act together and they've reduced the growth gap between them and Wal-Mart."

For May, the company said it expects same-store sales to rise 2 to 4 percent. Rival Target (Research) did moderately better with sales up 1.4 percent.

Said Perkins, "Eventually we might be left holding somewhat of a mixed bag because there were a few unexpected disappointments." Specialty apparel retailer Pacific Sunwear (Research) had a bad stumble with sales down 6.4 percent. Sales at Limited Brands (Research), which operates the Victoria's Secret, Express, and Bath & Body Works chains, fell 4 percent.

And No. 1 apparel retailer Gap (Research) suffered a 5 percent sales decline, missing analysts' estimates of a 2.4 percent decline for the month.

Even though it looks as though consumers are spending for now, Perkins cautions that a tightening could be around the corner.

"Longer term, it's going to show up," he said. "Consumers can't ignore the fact that interest rates are rising, the labor market hasn't exactly caught fire yet and energy prices are a burden."