I play healers most of the time in every game I play. As my latest healer neared 50 I noticed that even in normal play, not missions, etc., that the npcs got smarter and jumped me when I would use big heals. Of course, so far, this has been true in most games. However, I would like to add that while I may have aggroed at the beginning from putting a HoT on my tank, I'm more inclined on that one to believe it was my activity in the aggro range of the npc that drew the attack.
Iíve seen that too and not just with big heals. In HM TfB on Ciphas, Heirad and Kelsara, Vanguard tank was waiting to pull while Sage got out bubbles and I was stacking upper hand on my sawbones. Vanguard was close, but had not pulled, and he must had been standing there for 5 mins. When I stacked two slow-released medpac (HoTs) on the Vanguard tank we pulled. I was beyond range to pull, behind at least 4 other people right at 30m from the tank, but I had aggro. So while I agree that heals alone will not pull aggro, heals and proximity of healer or healerís target will pull aggro. Now I just stack HoTs on me and anyone behind me while stacking Upper hand before a pull.
Have to say, good group too, they didn't blame, they did moan about the pull. They went right into their jobs and we did not wipe. Just have to say that because I have seen way to many inadvertent pulls in HMFP end in a wipe for no other reason than people typing insults rather than playing the game and I have to give my group credit for covering my mistake.