Problem with U-Haul refill. Time replace my propane tanks?

You do what you feel is good for you. But i will say the exchange tanks are fine. There is no records of then failing more then a reguler tank. ( and that os rare to non existent, so maybe the rules keep that from happening. And for the most part propane is pretty darn safe if used corectly. The most problems people have are with the conection lines. Have fun.