There may also be another possible explanation, depending on your dose and how sensitive you are. Let me relate a similar experience I had with mushrooms (I know, its quite a dissimilar compound) and you can judge for yourself:
One time some friends and I decided to make mushroom tea, and really give it a hardcore go. We brewed up 14 grams according to proper mushroom tea preparation procedures, and split it 3 ways. One friend decided half way through his glass that he had enough, so I drank the rest of his. I also ate the chaff at the bottom of the teapot. One friend retired to his house, and myself and the guy who only drank half (We'll call him P) retired to P's place. I sat down on the floor in a pile of pillows and blankets and prepared for the trip. P put on some music, and I was starting to feel it come on fast. Then something peculiar happened.
I was getting excited, and had high hopes for the powerful experience that was ahead of me. I blinked. Suddenly it was daytime. I was in exactly the same position. Sun was streaming through the window. The clock read 7:30, when a moment before it had read 12:06. I felt crushing disappointment, I had fallen asleep and missed the festivities. It was not so.
I looked around and saw P sitting up on his bed, dozed off. I felt like I let him down. "Sorry dude, I must have fallen asleep and left you to it, I feel so bad." His eyes opened and he looked a bit frightened and relieved at the same time.
"Fuck I thought you were never going to come back for a while. I've been freaked out all night. I only dozed off a few minutes ago..." was his response. I was confused.
"Come back from what?" I asked, "I just blinked and next thing I knew it was morning, I just slept through it all..." P looked shocked and then burst out laughing.
"Nah man, you really didn't! You mean you don't remember a thing? Far out... You were sitting there with your eyes open saying weird shit that didn't make sense all fucking night. I talked to you but you ignored me, it was like you were off in your own world. I thought we broke your brain man!" P was laughing hysterically now.
To this day I wonder just what the fuck happened that night. P described a normal, if incredibly intense, mushroom trip, so they were not some bizarre or atypical mushroom. Who knows...
The point is, if he wasn't there to tell me otherwise, I would have thought I slept through the whole thing. Could you have possibly had a similar experience? I know Occam's Razor would lead us to believe that you simply falling asleep is a far more likely explanation that something akin to my experience is, but if I have learned anything from my extensive experience with psychedelics, its that the simplest explanation is not even close to always being the correct one when you're dealing with these compounds, and especially when dealing with the unpredictability of raw plant material.