YOU did nothing wrong.
They simply didnt want you riding with them...maye you were making their bikes look bad
Ive had plenty of people join in on a ride. I have no issue with it. As a matter of fact...during my MSF course it was suggested that if possible you join up with folks, in formation as it makes for a bigger, more visible riding entity.
by teh way it sounds....you didint rush up on em, you weret riding too close, you just werent one of them.
Life goes on!