Yeah that can well be a blackout. I guess it happens to everybody once in a while (it's a pretty common thing, although some are more sensible to it than others). I've had such moments as well. When I was 12, I biked into a parked car (also a blackout). Nothing happened, but it surely sucked.
As long as it doesn't occur frequently, I wouldn't worry. If it does, it may be wise to pay your doc a visit.