Talk to the guy and ask him for a good faith estimate. Do not pay any commitment or anything (especially if the ask to lock the rate for a fee). Get the GFE first. Then go to at least one other reputable bank and get a GFE.
Then compare the two. If you get two competitive GFE's then one bank will usually lower their cost by anywhere from 2-4 thousand. Depending on the loan amount. Local small community banks are almost always the cheapest for mortgage loans. They have low cost and a lot less profit written in their loans.
PM me if you want any specific help. I worked in this business for a bit.