I've been along our canal when the fishing matches are on (seems like they do several weekends). They all just stick their rods over the cycle path / towpath and leave em there. Dinging a bell seems to sort it out usually, but like you say, it doesn't half slow you down. You get the odd one who is arsey too and doesn't want to move their gear. Riding up as if you are going to do a trials style hop over their expensive rod makes em move it in the end though. It is a pain even if you're just going for a walk.
Personally, if it was an honest mistake, he left his rod there when the rest of them had moved them out of the way, you completely didn't see it, I'd have said oops, that was a bugger, and ridden off, same as you did. Obviously if you hammered through there shouting out of my way it'd be different, but otherwise, it isn't really your fault if he leaves a rod on the cycle path.
Joe