Experience for killing summoned fiends?

[Reidemeister]

I was wasting time killing summoned fiends (a cheese move, I admit), when I noticed something odd. Rather than the listed experience for the kill, I was received 10% more than expected. Specifically, 11k from Cacofiend instead of 10k, 13750 for Fiend instead of 12500, and 17600 for Gate instead of 16000. I was soloing at the time, and above the experience cap (with the cap disabled, of course). Curious, I went up to where my apprentices were making stuff, and I killed one, and found that I still got an extra 10% experience. Then I looked at the experience in a game with multiple characters, and found I couldn't make heads or tails of how it decided to assign experience on monster kills. Can anybody shed any light on the subject, especially the extra 10% experience that's coming from nowhere?

[Sojourner]

I've never received more than 16k for killing Pit Fiends (what you get using Gate), though I've never played a solo game. It seems to be a rather interesting bug. I, too, have the experience cap disabled, though with a full party I don't exceed it until final two battles.

[Loredweller]

What difficulty are you playing?
L.