Drove 30 miles no problem, stopped at a truck stop to use the bathroom for 10 minutes, and making a right hand turn onto the highway ramp my trailer came off the 5th wheel.

Tug test. Tug test it again. Double, triple fucking check, visually with a flashlight, that the locking jaws are secure around the kingpin with no play. There should be no space between the apron and the skid plate. The manual pull pin should be in the locked position with a safety catch over it, you will notice the bar is ALL the way in and it will show no gaps. When you do so, make sure the truck is therefore slightly back than forward so the kingpin is not resting directly against the locking jaws. One way to make sure you’re always in and in for good, is that you firmly but smoothly back into the trailer’s kingpin so that it actually comes forward when you lock in. Not gingerly, not softly, and don’t try to drive backward through it either, because then you could screw up your 5th wheel. I am not saying this is your fault, I am just saying from my own experience, with some shitty trailers and sometimes mechanical stuff on my Volvo, you have to do everything right and then some. Just to make sure. Sometimes in the motions of things we might tend to forget every single detail. Run it like a checklist in your head. It’s okay, a mistake can happen and we learn. Most likely someone screwed with your truck, but just do the things like I said, it really does work to go over everything twice. When you walk away, don’t let your truck idle, take your keys with you and make sure to set your truck so it can’t be effed with.