I may have mentioned that I have two 9 week old kittens 
It's been a while since I've experienced kittens this young (they're so CUTE!!! And DINKY!!) so I may be on here quite a bit in the coming weeks!
One of them seems to be a bit annoyed by her mouth - every so often she'll act like she's chewing something invisible, it's happened a few times so definitely bugging her somehow. Could it be teething?
She's let me have a look in her mouth and I can't see anything obvious - she's eating fine, and playing like a little mad thing. Shall I just keep an eye out or might she need the vet? They'll be going in for their first kitten checks/jabs etc soon anyway