Originally Posted by RawAlex

(6 out of 45 = 13% chance that any card that comes up is the one he wants, rounded up to 15 to allow for things like straights and flushes, etc. 15% over two cards = 30%).

That you got into that position preflop means that he had a pretty good chance for hitting one of those two cards ( 5 x 15% or 75%) and even a little extra chance with 5 cards to fill in a straight or a flush.