They could be going off because someone is shooting them or throws a grenade or say an enemy sniper sees the mine, he could shoot it at distance and trigger it.
Nope, I've been on the other side of this too, mines triggering on friendly vehicles for apparently no reason, in territory with no enemy activity and no weapons fire.
If an enemy sets off the explosives he gets all the kills, so there should be no grief. Only way you should get grief for your own mines is if you set them off yourself or if they go off automatically (which can happen if an enemy triggers them and a friendly is nearby).
Like I said, friendly mines have gone off on me too, with no enemies or weapons fire about. Something is causing vehicles to set off friendly mines, and it's been going on for a while.
