What's going on?

I started here with MFP on May 1. I have been faithfully logging my food and exercise daily. I am generally within 100 calories of my goal, and I've been burning btw 500-800 calories daily with cardio (plus doing weights/calisthenics but not logging those calories.) I eat back some of my cardio calories but not usually all of them. I have been consistently losing 1-1.5 lbs per week, with a couple of weeks of nothing lost but nothing gained back.

Here is where it gets confusing:
We started a kitchen reno this week so meals are fast food. I haven't been tracking my food faithfully and my exercise program has been on hold. (I have managed to get in a few walks and bike rides...but guesstimate those only burned 150-200 calories) So basically I have been eating at least 500 calories more per day, while not working out at all for the last 7 days. I have had to pack up the kitchen and have been doing alot of little jobs around the house, nothing very strenuous but busy.

I have lost 5 lbs in the last 7 days!!!

Here is my question:
Why have I been losing weight faster this week? Without even trying? Does this mean that I am exercising too hard/not eating enough? Did I just lose muscle? Do I need to add french friesand alcohol to my diet? (because that is what I have been eating and feeling really bad about it) I'd really like to know what's going on this week that allowed me to drop 5 lbs so easily. Not complaining, just curious as to what I need to do to keep it up...eat more? Not work out so hard? Add wine coolers to my diet?

I don't want to blow my progress and step on the scale next week to find that I gained it all back.

Any thoughts? Has this ever happened to you?