I've have this problem, too. I added in a few other mods, like Morph (I like being able to fit into 1 high spaces for my wiring). Every time I morph (the ` key), it heals me. I thought it was maybe that mod until I read your post. How do you unbind it? There's only 1 key bound to "GRAVE" in-game, and that doesn't seem to solve it.
It's an NEI keybind. Open your inventory, hit the options button in the bottom right, then keybindings, then world, and it's second from the bottom.