I have had the same problem multiple times in the past, and have never found a solution to why it happens, however, the fix is real easy. Just find the quick disconnect that has come apart, and put it back together. I have changed the quick disconnects, using the same model number, and after a while, even the new ones come apart. The Kubota dealer had no idea why, and at this point, the only choice is to change all the disconnects to a different design. The local Parker dealer, suggested that the pressures might be too high for the disconnect, and that they were designed to come apart as a safety feature. Finding the one that came apart can sometimes be a little elusive, but not impossible to find in a couple of minutes. You have to shut off the machine, and relieve all the pressure to get it reconnected, so that leads me to believe that what the Parker dealer has said is correct. It is always a high pressure line that comes apart, not a return line.