Running rich I think - any advice?

I was looking at my datamaster runs and cruising at 60, it shows that Lterm percent and Sterm percent were in the negatives...up to 30% I didn't know what that meant so I looked it up in help section. So am I running pretty rich or am I worrying about nothing. One more thing, Im getting ~13 mpg with auto and 4.1 and I think thats a little low. Thanks for any help.