Almost Frozen

Here in NY the weather has been in the 40s-50s-60s the last two or three weeks. Been driving off & on. Water only in the raditaor. Last night the temp dropped into the teens & only 20 today. Got home today to drain the water & the pitcock was frozen with ice, I took off the raditaor cap, the water in the top of the tank was not frozen. I went in the house & got the wifes blow dryer & heated the pitcock & in about 15 sec water started comming out. When all water stopped dripping I put about a quart of antifreeze untill I saw green comming out the pitcock. I hope everything is ok. Would this of hurt anything??

Bob