This happens to a friend of mine all the time and I definitely think it's because she takes too high of a dose. She's tiny and tries to push her limits, lol.
We'll literally be mid-convo and she'll be talking and she'll stop and say, "....Wait, what?" and she won't have any recollection at all of what she was saying a second ago. Then, when I remind her of what she was saying, she doesn't believe it and thinks I'm making it up..saying things like, "Yeah right, I wasn't saying that. Why are you messing with me?" She usually gets
really paranoid and it takes awhile of all of our friends convincing her that we're not trying to mess with her head or make her freak out.
I've had things like that happen to me during a roll, but not to that extent. I usually just misplace things like my vicks or lights, or forget why that walked into the house to get water, or try to smoke a cigarette without lighting it. 8) I find that when it does happen to me, it's usually on the nights that I've taken a big dose and/or smoked a lot of weed during the roll. I love smoking during a roll, but sometimes it results in me having a 2 second attention span.

If I'm rolling at home with my friends, it doesn't bother me much because I find everyone is just as forgetful as I am and we can joke about it. During a rolling night at home, everyone looks pretty out of it. It's funny if you're with people you're comfortable with...a bunch of friends wandering the house saying things like, "Hey, can you help me look for what I was looking for?"..."Okay, what was it?"...."Fuck, I have absolutely no idea!"
If it's happening really bad, just lower your dose a bit. That should solve it. It's perfectly normal though. It happens.