You don’t mention if it’s a purchase or refinance.
Mortgage rate quotes are really only “valid” on the same day as you receive them, as interest rates can change regularly and even throughout the day. So if you got one quote on Monday from Lender X and then another quote on Wednesday from Lender Y.... well, that is not at all an apples to apples comparison.
Don’t be afraid to ask a lender to match the better quote. They either can or they can’t. But before you do that, go get new quotes today from both, and then use that as a basis for your decision.
Rates are still hovering near all time lows and I think everyone’s crystal ball is glitchy these days. For a purchase with a set closing date, I’d lock in right away. For a refinance, if you love the rate, lock it and move forward. If you think rates might drop further, then just keep checking in with your lender(s) and asking for current rates.