It's important to check your credit report to make sure Experian, Equifax and Transunion have correct info for you. A friend checked his last week and all three had major mistakes for him and there were differences among them in these mistakes.
So, if you're seeing big discrepancies in your scores, check your report. (Actually it's good to check your report from time to time even if there are no discrepancies.)
https://www.annualcreditreport.com/cra/index.jsp