I think the technacal term for that is a "Brain fart". It's the same thing as when you get half way to your car and remember something you needed inside, or when you get up and go to the other room for something, and on getting there, can't remember what it was that you were going for.
It's alright though, as long as no one can smell the gears burning, you're fine. Trust me on this, I know from personal experiance.

*snickers*
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