The mushroom from the wine chest near the mage in the mushroom forest of act 2 shouldn't cause a problem. You should eat it, however, since it provides both your characters with a small, permanent luck boost.
In my post above, that 13 should be a 3 <img src="/ubbthreads/images/graemlins/eek.gif" alt="" /> so you may be looking in the wrong place.