Around here mountain bikers refer to that as 'the bump' and it is almost a badge of honor, except for the fact it means you crashed. It is very common among crashees. When I did my right shoulder I was never told a grade but it was about 9 weeks before I did much riding at all and a year before I could sleep on that side. The doctors told me that surgery would be a waste of time and 'you will die with it, not from it'. Comforting statement, that one. A friend who is a doc explained that the ac joint is always trying to pull itself apart so when the muscles get ripped it is practically impossible to get the bone back down without extensive surgery that is going to cause as much harm as good by the time they get done with you. Something to think about.

I'm okay now (that was over 2 years ago) but I don't do any more technical mountain biking, I just have fun doing less difficult trails.

BTW, I really like the Quasimodo reference. Two clavicles way up!!!!