I'm not so sure this isn't an urban legend. I've read of techs mixing it in water bottles and leaving it on their boxes for a year with nothing happening.
NOW, I could also believe that maybe you need to simulate engine operating conditions/temperatures to see gelling-- if such a thing occurs.
Thus, I am not saying I believe it is false for sure, merely that I'm skeptical.
Also, I think LOTS of mixing occurs from uneducated owners and you'd think this (gelling) would be a common thing techs see, but it doesn't seem to be a widespread problem. Here again I'm speaking in broad generalities with NO data to back up my statements, soooo.....