Appreciate all the great responses, Thanks BF. I will definitely stretch pre/post rides now, I am pretty confident I have a good fit, the BG fit thing.
This isn't the first time I've started out too much too soon, e.g. Ran 8mi. and tore groin, had nasty bruised going the left of my groin. I will take it easier and if I have to I will stop and rest.

All else fails, I can always carry some Cpt. Morgan's and a fistful of soma.