There are different length valve cores. When they installed your new tires they either installed the wrong one or it was defective. Go back to the tire shop and have them fix it. Valve cores are supposed to be tight. I would never loosen one, it might cause a slow leak.
Russ and Gloria, Sophie and Kaylee the Springer Spaniels
2006 40' Beaver Monterey, '2015 Grand Cherokee Toad , BlueOx Towbar, Smart Brake.
"Only those who risk going too far can possibly find out how far one can go"