You were fine, bobert. As you say: "I kinda stepped up on stage and tapped him in the shoulder and asked "You in trouble" and he nodded that he was and so I offered to tune his guitar for him and he lifted it as to indicate that he was accepting my offer..."

All perfectly normal and gracious, if you ask me. Good for you!

Some have hinted that there's a mysterious backstory to the antagonism of the other musicians. I suspect that the 'backstory' is that they were full of beer.