He's just trolling you. Did the mortar keep firing? That happens sometimes when AT guns get decrewed but don't "die".
I hope that Relic will take note of this bug and figure out how to fix it. I remember there was an un-recrewable 0 man MG bug in one of the SNF contender bouts between OMGPOP and VonIvan and it ended up hurting POP badly and probably cost him the game. That said, I think the bizarre behavior of some team weapons add to the "wtfomgbbq"-quality of COH. Ghost pak from COH1, anybody?
Off topic: Elite troops is still pretty bs imo. Instant vet goes against the spirit of the game and the tiger ace can still be gamebreaking.
On topic: Ghost pak was hilarious in coh 1 when an invisible crew would move keep moving the pak in death sometimes halfway across the map But at least they didn't shoot at enemy troops as far as I can remember.