I know the OP doesn't use macros, but wonder if some of the other posters are. I used to include a line to heal <me> (after <mo> and <t>), but this turned out not to be a good idea, because if your target or MO target is out of range, you'll heal yourself.

I fixed this by removing the line for <me>. The only drawback is that to heal myself, I have to target myself. I do this by mousing over myself in the party frame, which I have set to be active even when I'm not in a party.