It's not being petty if the pulls are being done intentionally. Party etiquette usually dictates that the tank must be the puller. Mistakes happen and people are not perfect. I think all tanks should be able to understand that at least. But their job is to pull and take most of the damage so others don't have to. Making their job harder helps no one. Dps doing too much damage or other players stepping in AoEs? That's something that might be a bit petty for tanks to get upset over. That's not really their concern. Might be the healer's though.