Rust on mosfet?

I've noticed that when I was changing my stock cpu heatsink with a xp-90c. There was some rust on top of the mosfet surounding the cpu socket. All of them. Is that normal? Ive removed it with 99% alcohol so everything is clean but Im still conserned.

I have a P5AD2 Premium mb.

on the mosfets? are you sure its not the caps? Not to insult your intelligence but mosfets are the black squares and the caps are the cylinders

Oups sorry I met tha capacitors. The little cylinder one.

http://www.pcstats.com/articleview.cfm?articleID=195

That's not rust, your caps are leaking. It's not a *huge* deal right now, but your either going to have to replace the caps, or the whole board in the future. Just keep an eye out and if they look too bad, discontinue use asap.