Ouch, sorry to hear about the off!
I've been on quite a few rides with you and must say you're a competent rider and certainly one of the safest I've seen. It could have been anything.. when you're leaning over it doesn't take much, be it a white line, a slight ripple/undulation in the road or even a single stone in the wrong place. Also, I've always hated your suspension so that could be what let you down (literally!).
The other possibility is that you don't generally push the limits of the tyres, perhaps on this occasion you went past your normal cornering angle onto a smoother part of the tyre?
Glad yr ok, and the bike will live to fight again another day too
May be a good excuse to save up for a braking & cornering course?