Like many addictions it all starts with the buzz we all get from standing on stage, no matter how small it is, and performing as a member of a band. Then it grows into not wanting to get off the stage. It's worse at Jam Sessions. The signs are impatience when others are playing, or even worse playing "your song"!! The major ones are the reluctance to get off after you've done some songs, in the belief that everyone loves what you do and want to hear more, or rushing up uninvited because "everyone expects you to sing or play on that song". If these are signs then the cardinal sin is making your set one that contains all the popular songs that musicians love to jam on. Leaving room for others is the best cure.