Mine do it too - it's hard to describe but they sit there, slightly jerking

backwards and forwards, and if you listen carefully there's a tiny squeak as they do it (they also seem to do this when going to the loo sometimes!).

I'm not sure if this is hiccups or part of a respiratory problem. It normally lasts maybe 20 seconds or so, and stops if you distract them.

Is this what others are experiencing?!

Ali