Brakes Locking Up on 91 F150

I recently had the back brakes replaced on my 1991 Ford F150. A couple of days later the front wheels were getting tight and now lock up when the truck has been sitting. I have to put it in 4x4 to get it to move then shift to 2 wheel. The truck is man. trans. and has 302 with 170K miles. I concerned that this has happened only a couple of days after having the back brakes done. The back brakes are very snug and the mechanic told me they would break in shortly. Is there anything that can be adjusted or where should I start looking?