Rad Leak

Bought a 22" restored rad from a member here that was suppose to be brand new. Still have a hang tag showing mopar number and size. I installed it and filled it with fluids and sat for 3 days and was ok. Got engine all hooked up and started it and ran for 20 minutes. Next day I noticed a 1" diameter puddle on floor and looked at rad ....the lower rad support also had antifreeze sitting in it. Let the car sit while doing the dash and interior wiring and it did not leak over the last 2 months and when i started it again ...sure enough ...a tiny puddle on floor. I'm guessing it only leaks under pressure and maybe only about an 1/8 glass full of fluid ...mind you i only ran it for 20 min. again. Looks like it was wet on interior side right in front of the clutch fan. Is there any quick fix or should I be looking at taking it out and off to the rad shop in the city.