Google Product Forums
Re: Galaxy Nexus power button doesn't always work
Google Mobile Help Forum
Android Devices : Other Google Products :
I have not. Apparently this isn't a very widespread issue.
Had an occurrence yesterday during a call that was on speaker with the keypad activated. The call completed but I couldn't reactivate the screen after it was done
Another time just now when powering on to see if my indicator light was text, email or gtalk. Tried to turn it back on a second ago and nothing..