2000 Pontiac Sunfire, tires sqealing

I just got the 2 front tires changed on friday and they started squealing the same day, I brought the car back and the guy drove it for about 2 seconds in the parking lot and he said the brake pads need to be replaced, my question is, isnt it a little odd that my brake pads need to be changed THE DAY I get new tires put on the car, I read around and it could be a few different reasons for the squealing, improper tightening sequence of the lug nuts, missing springs or anti rattle clips in the brake caliper, im just wondering, could the mechanic of not put the tires on correctly, or done something else, and thats why they r squealing?