First of all you need to get a copy of the credit report. The lender has to tell you which credit report they have used in making of the determination. And you will get a copy of the credit report for free. That is what is provided now under the law.
You need to make certain that your credit is on your credit report. It is not unusual to find somebody else's credit on your credit report. You also need to be aware of, there is identity theft everywhere and you want to make certain that somebody else isn't using your credit. So it is important to take a look at it on a periodic basis. Right now they have free annual credit reports so I highly recommend that you get it out and look at it and make certain everything on there belongs to you.