Disclaimer: I am still very on the fence, but suspicisions are starting to lean a bit...
With that being said, I wanted to play devil's advocate for a moment (really I'm just bored at work and trying to kill my last 40 mins, but who's here to judge?

). Let's say for a sec that JC is truly innocent of any foul play - and perhaps just guilty of being an irresponsible stoner. A lot of these fumblings and bumblings
could be attributed to the fact that he's just trying to cover up his habits for the day. Having done nothing wrong, and not wanting to appear as a total slacker to LE, it wouldn't be that weird to try to hide that you stayed up all night getting high and then slept all day while your girlfriend was supposed to be off working her tail off. And so, the 4pm wake up becomes "oh, I texted her this morning." The being so stuck in your own little world that you don't even
notice something's wrong until that night becomes "uh, yeah... I worried all day, but..."
In the context that he might not have been certain that something really was wrong (and may have even been a bit embarassed to call 911 & speak to LE, if she ended up say, at an art show she'd already told him 20 times she was going to), it doesn't seem all that odd that he'd gloss over facts about
his day to just seem slightly more engaged, responsible, etc. After all, if something is wrong, you want LE to take you seriously, and not view you as some overanxious stoner who misplaced his girlfriend again.
The problem is, something
was wrong. And now you have the entire world, Nancy Grace, facebook lurkers, and people like me - who are too excited about happy hour out in the sun to get any work done - picking apart your every move, and of course realizing the timelines and stories you gave don't add up at all. Odd? Yes. Overly suspicious? I'm not sure.
And again, I'm just playing devil's advocate here. I still think JC has done some pretty suspicious things. For me, though, the fact alone that he appears to be operating on stoner time isn't necessarily one of them.
JMO.
ETA: none of this relates to any of my own frustrations or experiences with former stoner boyfriends. I swear. =)