If he can identify you (he did see you behind the wheel) when he went by, as you mentioned he looked pissed, he might get you later... Dunno if u-turns are legal there, but here, you would probably get at least one of the two tickets you are elligible for...most coppers here write 20 k over (12 mph). So you mite get one or the big bonus..... none....60 in a 50 is not that bad...i doubt he can stop you hours later after the fact and give you a ticket...and if he does...you only did 10 over.
Don't worry too much. If he got your plate, you would have met him by now. If he didn't, he may stop you later... and remember, he did see you, so don't pretend like you car was being driven by a space alien and that you were in another county at the time. Just man up and treat it as a learning experience.