Perhaps the effect of the drug might have carried over to the next day - I’m sure this could be verified, but it’s something I’ve experienced with other drugs. You skip a day, intentionally or accidentally, but your system hasn’t flushed everything out so the drug is still taking some effect.
It was actually over a longer period than a day. I would like to think that some part of my brain is no longer associating alcohol with the buzz I used to get. It seems far fetched, but plausible? The other side of it is I definitely would feel the "buzz" of alcohol before I actually drank it, such as when I was walking home from the store carrying booze -- I would feel elated.
To be clear, the "buzz" I refer to is straight up pleasure, not intoxication. On naltrexone I felt the intoxication without the pleasure. It made me think, is this what it's like to drink alcohol when you are not an alcoholic?