If your weather is like ours here in Florida, I could see this happening. The pressure regulator limits the water pressure going into the hose and there is a valve in it that keeps water from going back into the faucet. So if no one uses any water in the TT, the water is trapped in the hose with no where to go. The sun will really heat up the water in the hose and will create some high pressure, not to mention very hot water. You may want to try relocating the pressure regulator to between the water filter and the hose. The hose can take a little more pressure.
After seeing a motor home with water running down the stairs and coming out of the storage areas, when we leave the TT for trips to town or sight seeing, we always turn off the water and I open the "Y" at the faucet to lower the water pressure in the hose.
We are constantly going though hoses in the back yard here in Florida. This year we have been turning off the water at the faucet and no massive water leaks this year... so far.
2013 Jayco Eagle 284BHS
250Watt Grape Solar Panel, MorningStar MPPT 60 Charge Controller
1500 Watt Ramsond PSI, 2 Trojan T145 Batteries (260Ah)
2 - AirSight Wireless IP Cameras (used as rear view cameras)
EnGenius WI-FI extender, D-Link wireless (n) modem
MagicJack Internet Phone
2012 Ford F150XLT, EcoBoost w/3.73
157" Wheel base, HD Towing Package
Our Solar Album http://www.jaycoowners.com/album.php?albumid=329