Is it a draw?

I was playing a match yesterday against an opponent whose rating was about 150 points higher than mine.  I hung in and at the end the material on the board was as follows:

Me:  King and rook

Opponent:  King, rook and bishop

I kept telling him that it was a draw.  Someone please tell me, was I right?

It is a technical draw, but a somewhat difficult one for the side with the lone Rook.

@OP: In some positions, I believe a win can eventually be forced, but since it requires more than 50 moves, the game would usually be declared drawn before the mate could be achieved. Also, actually getting the sequence of moves right against best defense would be incredibly difficult, so achieving the mate is almost invariably infeasible.

Still, since the fifty-move rule must be claimed and is not automatic, your opponent is within his/her rights to try to checkmate you, since he has the Bishop.

I kept telling him that he would run out of time before the mate could be achieved.  I was actually trying to help knowing full well that the mate could eventually happen.