When people get drunk their prefrontal cortex (the part of the brain that modulates our instinctive behaviors) shuts down. If you don't do this when you aren't drunk (or think about it), and it's a one time thing, and of course after clearing things out with your GF by apologizing to her and explaining that you don't do or even think about that when you're completely conscious, then I think you don't have to worry too much about it. Just be concern with her well-being and let her know that you care about her.