Your friend was not still high. I really believe the problem with some people and weed is it makes them think and feel ways they are afraid to think and feel. It makes them introspect on a deep level and in a world so full of mindless, brain numbing distractions all around us some people can't handle it because they never spend the time to introspect anyway. So when they finally do it's like they're a stranger in their own body because they barely know themselves. Hopefully your friend can realize that looking in is a good thing, not a bad one.
The truth is, cannabis is not harmless and she might simply be having a bad reaction to the compounds inside the substance. I remember I used to get high before school and I swore I would feel high well into the next day... but I wasn't "high," I just had that afterglow for a lot longer than any of my friends did. However, it sounds like she'll probably be fine. It's just pot, after all. That being said, I'd probably tell her to stay away from the stuff, and would definitely encourage her to let someone know what's going on if this goes on for much longer. That's definitely not normal, but she'll probably be fine.
<-- thinks all this type of posting is False Flag. My wife is an ultra low dose user. No way she's stays high for days. It acts on her just like it does on everybody else. Smoked-Vaped = wears off in 45-90 minutes. Edibles = 8-15 hours. It takes a really massive dose of well made edibles to hammer someone silly for 30 hours. Even then it wears off and leaves no long term effects. My 2 cents. BNW