No problems here.

For what it's worth, if there's snow on the arm which comes out under your dish (the LNB, I think it's called), I'd say that explains it. Have a look on the Digital Spy forums and you'll probably find a host of people having similar issues.

Obviously take extreme care if you decide to attempt to clear it - you don't want to knock it out of alignment since that might leave you with no signal with or without snow.