This isn't the end of the world, since the other two of the "big three" credit reporting agencies (TransUnion and Equifax) will still give you a score. But because all three of them collect different information, you might not be able to find out if Experian's score is out of whack compared to the other two -- and deal with that fact before prospective mortgage lenders see your score.
For details, see this Wall Street Journal article.
