Steven is on the money.
The one thing I want to caution you about is neurosis in regards to diet / BF% / strength numbers. If you are a hard charger and dedicated to what you are doing you, which it seems you are, you can over think it sometimes. We all do.
You are a young guy with the rest of your life ahead of you. The key for you now is to establish healthy habits that will provide you health, athletic excellence and longevity.
I think you will find that most of us here are aware of what our BF% is but look more at our performance numbers to determine progress.
A 10 day trip with a radically different die,t probably was combined with a lack of rest and less exercise than normal if any. The majority of that spiral you talked about is probably mental.
I would get comfortable with what my short term goals are (mass gain, performance) and focus on that.
Don't worry about what you might have lost or what changes took place, they are done. Let's get a good plan going forward and kick some butt in 2008.
What we think, or what we know, or what we believe, is in the end, of little consequence. The only thing of consequence is what we do. -John Ruskin