I have been waiting for this to happen to me. Every time so far I catch myself right at the last second, but I know that sooner or later I won't. xD
On a related note, one of my art professors routinely licks his paintbrush to wet and rinse it when he's drawing away from a water supply (he draws with markers and uses a little teeny can of white acrylic for highlights), and he's fine. A little crazy, but there's no way to tell if THAT came from the paint or not.