The 19 jw kid who works for me brought this up (it would have happened before he was born.) He said his mother (who was the *earthy* type - I remember her, neat english woman) was at the famous John Denver concert when he asked all jw's to leave.
If it happened, I think the reasoning was: He was sooooo goody-to the earth type-just waiting for the clensing of the earth. I'll bet he was inundated with jw books, pamphlets, etc. Got tired of it - and reacted.
A sister I know went to Hawaii for convention back in 70's. Remember Don Ho - the lounge singer? They went to one of his shows. He mentioned the convention, and asked all witnesses to stand (very friendly style). They did (quite a few of them). He then sang Star Spangled Banner. They quickly sat down - he laughingly apologized.
With how the tennis girls reacted - it seems now they could have stood for it and put their hands over their hearts, right?