Bugged game

Hello,

I'm currently playing a game and did encouter this strange bug.
Was wondering is this is a common bug in here

Game can be watched at http://www.chess.com/echess/game.html?id=42030433
Just move back 2 steps... And say -uh- ?

if you are talking about 5. dxc6 it is called en passant and is a legal move.  check the rules under the learn tab at the top. 

Damn... I really didn't know about that move.
Now i'm feeling noob. Thx for informing me

no worries.  seems to happen to almost everyone. 

Actually it started out as a bug and instead of fixing it they just made up a name for it.

The game designer's universal maxim: It's not a bug, it's a feature!

I was fortunate to learn that move at a young age.  By the way though, if you want to specify a point in a game, you should probably list the move number instead of "a couple moves back", since your game has progressed considerably in this time.