The auto valves can be prone to sticking on or off from time to time especially after its had a bit of use and if its not been cleaned through well enough, summink i didn't really do often, but a little tap on top of valve usually sorts it out till you get chance to clean it properly. I bought a spare auto-valve cus of said reason that was ready to go if shit happened and i just replaced the sticky one to clean through. Maybe it was a chink in the mk1 auto-valve that was in the older auto-pot system, cus i see the newer auto valves are really different, but yes i thought id mention it. Tubing can also become full of gunk after a few grows if your in a hard water area. Just a few things to keep an eye out for from time to time with that system.
I see you say might start using "TheEnd" ferts ask the GHO guy if those ferts can gunk your lines up cus ones your using wont so much. Tbh |"TheEnd" ferts may even keep lines cleaner cus i think they contain some sort of goodies, but im not sure, best ask him.