I hate it when people Regen me before a pull, and I don't do it to other people. I can deal with it when it happens and the mobs try to run past me but I'd rather not. Just wait until the tank stops; if he's going to die mid-pull from damage then Regen isn't going to save him anyway.

It's kind of in the same category as pulling ahead of the tank IMO. You want that aggro? You got it, buddy. I'll warn you once or twice but don't expect me to save you the third time.