If you were drinking red wines -- and a LOT of wine -- there may be an issue. (We've covered this in other threads). Drinking hard liquor or mixed drinks probably shouldn't have much significant effect.
The liver deals with alcohol differently from the way it processes warfarin. Unless you've got liver problems, you probably shouldn't worry.
I'm not a big fan of monthly testing - even if you're stable. (And I'm one to talk - in the past, I went MUCH longer than a month between tests).
One of the mantras many here have repeated is that you should be consistent in diet and activity. Drinkig a lot over a great weekend is certainly inconsistent -- if your diet changed during that weekend (lots of salads, perhaps?), your INR may be effected by that change. SO - sum total - if diet changed, activity changed, and you add alcohol to the mix, it MAY be possible that there's some effect on your INR. At least, it might be, in my opinion.
(If you had your own meter and were able to self-test, this whole discussion may have been moot)
