Yep, you may have some of those. If you are moving to a condo or townhouse, or a house that is part of a homeowner's association, be sure to investigate maintenance costs and assessments. While you're at it, ask for a record of the past five years of rate hikes. You want to have a sense of whether you are going to face much higher assessments going forward.
If your new place is appreciably smaller, make room in your budget for inevitable new purchases, such as replacing an oversized sectional or king size bed that won't fit in a cozier place.
And don't forget that when you sell, you'll have the 6% or so sales commission (assuming you own your current home), plus the cost of the moving van and all the other fees associated with schlepping your possessions to a new place.
Bottom line: Running the numbers is key. Tot up the annual cost you currently pay for ongoing expenses; as you start shopping for a smaller home, get estimates for what those costs would be at the new place.