thats mental, whas he a proper 'mtb'er? all kitted out, or just some random bloke going for tootle around? cant imagine a proper mtb'er being like that towards one of there own....
plus the fact you both crashed into each other, it was'nt as if he was stationary and you ran into him, both from what ive read were to blame/or not which ever way you look at it....
I can imagine the shock of being hit by a fellow mtb'er is a bit bemusing and i dunno if anyones initial reaction would be to hit back, regardless of whats being typed on here.....
Just seems a most bizarre experience, i'd just put it down to that, and try to forget about it as you are doing....not everyone's like him most mtb'ers are friendly, but theres always going to be a few cocks around, like there is in any sport...