I'm guessing that this has to do with the humidity. When I bake and set things out to cool on a cooling rack, I've had a problem with things (especially cakey things like muffins) becoming sticky on top. It is like they absorb all of the moisture out of the air while they are cooling. I know they are cooked all the way through, and they aren't sticky throughout. Does anyone else have this problem or have suggestions to fix it?