Most of the descriptions of lapses or slips are fairly different from Morticia's incident. The majority of you made a mistake when you were not paying attention. That happens to everybody nearly daily. Not knowing where you are and where you are going while paying attention and actively trying to regain that knowledge for half a minute is something quite different.Stress is a possible harmless explanation. So are sleep deprivation or effects from drugs (including medication and all legal drugs). If it's not one of these possibilities or if it comes again, follow Doug's advice.
Wolfgang