Hey guys. I have 2 gold Apple snails, one in a 20 and the other in a 29. I've noticed for the last month or so both of them will just release themselves off the glass and fall to the bottom. They do this often and from the top of the tank. I've never seen my nerites do this.
I like to think of it as a form of entertainment and excitement for them (and myself!)
I think they have to enjoy it, at least the mysteries. My nerites only end up doing it if they picked the wrong time to be riding around on one of the mysteries and boy do they try to get off quickly afterward. When I had a bubble wall they would ride up the bubbles instead of climbing.