a77 Squeak...

I got the a77 about a week ago and after a few days of use it has developed a squeaking sound on powering up. It seems to be coming from what I think is the ring that moves the aperture lever (?) on the lens. If I remove the lens (any lens) and switch on I get a squeak the first time then just the usual click on subsequent power ups. Re-attach the lens and the squeak returns! Any ideas..? Could this be a sign that something is about to fail?

Everything appears to be working OK, by the way.

Thanks in advance,

Mick.