hot weather. Sweating.
Water loss. Diet change with less carbs? More water loss.
Don't worry about it. Real muscle isn't really lost that quickly.
After 3 months of absolute hell that included weeks of not eating, eating only comfort foods (and not enough of those), and a week or so back on the anabolic diet...then repeating the whole crappy cycle...even with the 20lbs of
weight loss that I didn't want to lose...
I still got a compliment on my arms a few days ago. It was, "damn, your arms look good, pretty big too". Well, they aren't. They are smaller than most people's but still don't look too bad even after the last three months. And bodybuilding isn't even one of my goals.
So, if a 38 year old/non bodybuilder can still get compliments from the 22 year old chicas after 3 months of terrible eating and worse workouts + a summer spent mostly just conditioning with cheerleaders...you have nothing to worry about in 3 days.
(even if the chica was just scamming for a date she's not gonna get. Hell, I'm taking her to the nickelback concert as a friend, that's enough isn't it?)