As a tank, it can be slightly annoying, more or less depending on the situation itself. It doesn't annoy me enough to say anything in chat, though I certainly yet at my TV when it happens lol. If the healer is going to do that then they better be OK with possibly taking a few hits until I get back to gather them up. So if you don't want to deal with that, then don't regen pre-pull. Otherwise it's all gravy.