Rate have gone up since the middle of January. Probably just over .5%. Several things could be possible.
1. Your broker told you he was locking the rate but didnt so that he could play the market. Lenders pay brokers based upon the rate they lock you in at. If rates would have got better during underwriting he would have made more commission. If rates got worse he would either tell you to take a higher rate or honestly tell you that he got burned and would pay the difference.
2. He may have forgot to lock this or the lock request faxed to the lender did got go through. Many lenders are automated so the later shouldnt have happened.
3. There are several different risk factors that go into determining an interest rate. If he was adding the pricing adjustments for these risk factors incorrectly he could have quoted you a bad rate.
4. Rates are usually locked for 30-45 days. Sometimes brokers will forget to extend these locks before they expire. In that case, the new loan rate would be subject to worse case. Meaning, were rates better on the original day or current day. Again, rates havent increased by 1.25% though.
Is your loan an investment property loan?
You may want to ask him for a copy of the original lock confirmation that the lender would have sent back to him. If he refuses, contact the owner of the company. You may also want to contact another mortgage company to compare. Going back through the process would be a drag though.