Glitch or hack in MW2?

My little brother was playing MW2 today. (I play Black Ops, but he just likes MW2 better). I was sitting there then he was like "Come look at the guns I got!" so I went and looked. I took the controller, he had an ACR grenade launcher, so I switched the gun and then he had a FAMAS Bling (silencer and I think FMJ), so I switched it again so it would go back to the ACR so he could keep playing and when I did it switched it to a silenced Raffica. I re-did it like 3 times just to make sure I didn't accidentally pick up another gun while it was switching so then it would look like he had 3. But he didn't, so he was running around on MW2 with 3 guns. Glitch? Hack?