Every little "group" has their own little "code" . I've been biking 36 years and thought I knew about most of these little "nuances" , but recently I came upon a group of about 20 mixed cruisers , guys and gals , rode behind them a mile or so (with a respective distance) , and as I went to go left around them on a 4-lane , chick passenger in rear turned , opened , and tossed a FULL 48 ounce drink on me , drink , ice and all . I was outnumbered and it was a chick , so I let it go .
I still to this day don't understand it . So much for comeraderie .

Bottom line - there is a general code of conduct in riding , but there are abberational little "groups" .
Go your own way and leave them to their pitiful little selves .