My reptile room tends to get really warm with all the lights on, so on hot days I'll have the ceiling fan on low to help keep everyone a little cooler so they aren't gaping. However, here in FL humidity is never a problem that I have to worry about
As long as it's not blowing right on your cham, it's fine, in fact, it helps keep the air circulated.
I have a 12'' fan hanging from the ceiling in my dinning (errr.. I mean BUG) room. It's several feet from the chams.