Why can't I keep a PWS hose on my car?

[Cappy]

It's absolutely insane. The wife's teally has only 41,000 miles on it, and all the hoses and belts appear to be in great shape...except one. It's a low pressure return hose (or so I've been told) going back to the power steering pump. When it falls off, I get a nice big puddle of fluid under the car, and then when I start it up, the rest of the fluid comes pouring out, so I can't drive it without burning up the pump. This has happened FOUR times in the past six months! The first two times, they blames it on the fact that they were using a "similar" fitted hose, but not the exact fit. The last time it fell off the dealer ordered the part from Japan. It cost me a whole $12.85, but they had to give me a loaner car for a week. This week it happened again. While the car is parked - this time it was just for an hour or so - the hose simply falls off! The last two times it has been on very cold nights (10 degrees F) but I can't see how that's got anything to do with anything.

Has anyone else ever experienced this before?