King and knight VS king and bishop

I was left with my king and my light squared bishop and my opponent his king and his knight.  I ended up throwing away my bishop to attain a draw by insufficient material.  But I was wondering... how was a checkmate possible with what we had?  Who was able to do it?  Can anyone show me?  I can't figure out a set-up where a checkmate would happen...

A checkmate can't happen.

Then the game should have ended as a draw by insufficient material, but that didn't happen until he took my bishop I gave him.

Well I guess it is theoretically possible that a checkmate could occur, for example:

but in practical play you wouldn't be able to force that position.

Aha, bingo.  I figured it out.  But white would have to be pretty dumb to do something like this...  It should be called a draw anyway for white won't make the dumb move to fall into checkmate.

Well, I guess it can go both ways :)  Thanks

It's good to be aware of these kind of smother mates though in case they ever can occur.

Deffinately.  In a game with other piece still on the board, it's a bit more possible that black or white would move thier pieces this way, not knowing that their opponent would just have to move one piece to mate.