Anxiety Support Group
Anxiety is a physical condition marked by intense and persistent feelings of distress, fear, angst or dread. General anxiety caused by routine day-to-day stresses usually passes quickly and is experienced by almost everyone at one time or another. However, such feelings that linger over time and are very difficult to cope with, and which lack a clear cause, may indicate...
Read more : http://www.ehow.com/how_7332111_heat-mayonnaise.html
For mayonnaise, I would not worry at all! I've eaten hot mayo, mayo that's been left out on the counter, old mayo, reheated mayo, you name it. I've never had a problem. Like crazyhaze stated, commercial mayo is packed full of preservatives for a lengthened shelf life.
P.S. When in doubt however, don't eat it. My mom got upset because I threw away some Tamales that she left out on the stove all day and night. I wasn't going to take any chances.