Not paddling-specific, except one
The fairly few peeves I’ve petted turn out, on further thought, to be more about general etiquette issues, not paddling-specific ones.
The only one I can think of that’s unique to the sport is when someone, trying to help me when landing, grabs my boat and drags it to land. This has happened when I didn’t need the help, and I don’t like having the boat dragged, regardless whether it’s plastic or fiberglass. I know the person is just trying to help, so I try to intervene with a hasty, “Thanks, I can get out OK by myself.” But after failing to intervene quickly enough one time, now I eye the landing area and try to get there when nobody is close enough to do the instant grab.