Look at it on flickr, I'm guessing you shot it wide open for that focal length? Wondering as the shutter speed is quite high and you can see the edges getting soft. For work like this I'd recommend staying at F/8 unless light conditions demand you drop down, and even then I'd push my ISO to 200 before losing clarity.
On a personal taste note, I like a bit more recovery in shadows and then locally adjusting the contrast when dealing with snowy mountain situations, despite how flat the overcast weather makes the capture.