Do they like falling over?

I have one girl who will try to climb up the glass and proceed to flip herself upsidedown. Rights herself right away, then goes right back to it. At first I was worried about stereotypy, worried that she wasn't getting enough enrichment, but now that they're in a new enclosure with plenty to climb - I'm wondering if this is play behavior somehow.

Wish I could figure out what's going on in their lil heads~