It depends on what type of accounts are on your credit report. Just having a score above 620 does not guarantee a loan approval. I agree with Bradley... go see a trusted loan officer, have them pull your credit & do a FULL review including income & down payment. That is the only way you'll know for sure.
Realtors want to know the pre-approval was done properly and everything was reviewed before they start showing you houses on a Sunday afternoon. Good luck!