When a pro DPS pulls off me I let him have it, it'll be dead in two seconds anyways. When a nub does it, I pull it off the healer after he's gotten himself killed.
It's nice to see this attitude, honestly. Right or wrong, there are definitely situations where DPS can out-threat their tank, and they know it, and they're not afraid to take a little damage. If it's becoming a problem for the healer, they need to watch it though...that's just considerate.
If they tank wants to moan excessively about not having 100% of encountered mobs beating on them 100% of the time though, then that's a problem as well.