Tactical shot leads to uncertain ending

In my last club game I had the White pieces and played e4. My opponent elected to play the sicilian ... I played the closed variation with 2.Nc3, hoping to get a Grand Prix Attack. Interestingly my opponent elected to play 4...Nf6? which although not a blunder, seems not to be a 'book move'? I'm not sure what his intention was but I will be putting the game through Fritz at some stage ...

As the game progressed it it turned into a classic fight for the center and the e5 pawn became the focus. After some analysis in the curry house afterwards an IM colleague had a look at the game and noticed that Black can actually win a pawn but I can't see where? Another candidate game for Fritz!!

(I found out after the game that my opponent was graded almost 300 Elo points above me at 1840 Elo. This game had a sharp conclusion which led to uncertainty and served me well!)

As usual, any comments welcome ...

Chess Diagram 1 - Closed Sicilian - 2.Nc3

Note: I offered a draw in this position and it was duly accepted.

PGN Viewer courtesy of http://chesstempo.com/