I have been experiencing excess fan speeds too . . .
It sped up when I was logging into WoW, which it never has done before, and when I was capturing some video in FCP. It never did it before, but it doesn't last that long, maybe speed up then speed down only lasts like 30 secs. It doesn't really bother me though, becuase those are things that might tax the computer and warrant more cooling. If it did that when I was just on the desktop, then I would be annoyed.
But yeah, I think that the 10.3.8 update changed something to the fans.