Yes--as a Disc priest healer, who also has a dps Warrior, I've had the same experience--often during the very first trash pull, in a dungeon...the last time, it was a poor pull, on the part of the tank, and the healer drew aggro. I immediately tried to pull the mob off that healer, and we managed to get all five mobs down, but very messily.
The healer went in to a full rant, flaming me for being an idiot, and stating they would not be healing me, for the rest of the encounter! Ok, well, I stayed around, long enough to make sure that healer died, from his own inability, before I left group.
Bad time? Yes...but, as a healer, I would have to be provoked, much more than that, to ever flame someone, or not heal them.
If it's simply undergeared, or inexperienced players, as a healer, I consider it a challenge, to see if I can keep them up...it can be more interesting than running through with overgeared players, sometimes...really!
-"Just like a buzzin' fly, I come into your life, I'll float away, like honey in the sun..."--Tim Buckley