which bit? the whole lid as it screws onto the pot/jar?
I've had this happen to me just once in the whole time I've been using my I-R (since early jan).
If you think the lid is too loose, there is a screw at the top of the handle, loosen this, push the metal strip which surrounds the pot down then tighten it up. Sometimes I can't be bothered to get a screw driver out, so I just push down on each of the little tabs. Something which may also make a difference is a smoke vent... the added weight may help to stop it from turning if it is a little loose.
This is a minor design fault, if you ask me. Personally, I would have placed a strip of rubber under the metal band to stop it from slipping on the glass, which it is bound to do.
Let us know how you get on. Oh and it is about time you signed up
D