The mind begins to wonder as mental sharpness may subconsciously change near closing time. If it wasn't timing, and it wasn't a lack of concentration, then it may well have been an "optical illusion" or one of millions of other possible factors (lighting, hunger, warmth, etc.).
Success or failure is a very personal matter. The good news is that you now recognized some of the symptoms. You have probably already heard the jokes about all the pretty chicks left in the single bar near closing time. The only drawback is the mental hangover and/or mental guilt-trip left afterwards. Don't over analyze things the next morning. You'll quickly get over it with more experience.
