Nah, you can leave it in there for a couple of days. For some reason, they seem to prefer it when it's starting to get a little gross (they eat rotten fruit in the wild, so that's where it comes from). If it's got mold on it tomorrow, though, go ahead and toss it.

I feed mine Clark's Gargoyle and leave it in there for a couple days. I normally feed at night, and they don't start eating until the next day.

Yay for chocolatey goodness! I love the dark chocolate cresties. When I get the finances to get back into breeding them, I want to start a chocolate project... get some really dark, dark brown cresties and see what I come up with. Maybe that elusive black one