I usually have a glass of merlot or a cocktail before bed most evenings. About every two or three weekends I go out with some friends and drink 4-6 drinks, usually fine, hard liquor and some hoppy and exotic beer I've never had before.
It's not a problem until it affects your health or your goals. For some people that takes very little and for some it's not an issue. For example, my mom used to have a glass of wine and become a raging bitch for hours on end. Me or my father could drink until we passed out and never get angry if we wanted to (never tried it).
Lesson here is 'know your limits.'