I am a mortgage banker that can fund loans in all 50 states. If your income qualifies you and it can be documented, and you also have verifiable assets then your scores are not sub-prime. 620+ should be able to get great rates assuming you have correct income and asset documentation.
The only exception to this would be if you are trying to obtain 100% financing, in that case, yes minimum fico scores have been raised to 680+ with most major banks.
Feel free to pm me if I can help you out and good luck with your house hunt!