Upper Radiator Hose Came Off for "No Reason"

I have an 2005 Pacifica with 200k. I was driving the other day on the highway and the heater started blowing cool air (I had the heat on), then the temp gauge fluttered and went to max. I pulled over right away and popped the hood. There was some steam but after it cleared, all that looked wrong was the upper rad hose just pushed off. I believe the rad hose and spring clamp are original from 2005. The hose was still nice and pliable and the clamp was really strong and difficult to squeeze. I was near a NAPA so I got a new worm gear hose clamp and a jug of antifreeze, slid the spring clamp back a little so I could put on the gear clamp, put in the antifreeze/water mix. I had a little trouble with air locks but think I have them worked out now. I've driven 100km with no issues and lots of heat. The gauge stays in middle or normal range,

My question is why would a seemingly good factory installed hose clamp weaken to the point that a rad hose would push off? I've talked to 3 long time mechanics and they have never heard of this. Especially if has been in place for 200k with no issues. Also, just an fyi, there is no compression in the coolant system from a cracked head and no water in the oil. The engine runs fine other than the hose coming off. Also, vehicle is locked at all times when not in use, so no one could have intentionally done this.

Any comments or insight to why this can happen would be appreciated. I seems nearly "impossible"

Odd problem but with cars anything is possible. My guess is the clamp got weak after all those miles and pressure made the hose slide off. The worm drive clamp will solve that problem.