Should I stick it to Game Stop? Or just take the games back?

[xXI GaMe IXx]

So yesterday I went to go buy Infamous, Metal gear and little big planet from Game stop. I took in a few games to trade I took Batman Arkum asylum ($13.00 store credit) I traded in (Alan Wake $18.00 store credit ) and Gears of war 2 ($12.00 store credit). While I was being rung up I noticed they sell most of these games almost $25.00 more then what they gave me oh well right. So I get the bag that the Customer service rep handed me walk out of the store.

When I get home I noticed not only did they give me the credit but the cashier gave me back my games? He literally put all 6 games in the bag and I'm at home thinking dam Should I take them back or just keep them? Let me tell you that I'm the type of guy that usually gives money back to a cashier if they give me to much change. I'ts just that this time I don't feel bad about it I feel like they have really robbed me with all the games I have traded in before. However my wife keeps throwing it in my face that karma is a *itch so I'm going to go take them back what would you guys have done?