I did the same thing when I went on a trip last spring. I had just gotten a light gray small MP for my birthday and wanted to take it with me, but was afraid of getting it dirty. I used an XL Longchamp tote as a carry-on with the MP in a dustbag inside.Last time I flew, I had a bigger carry on bag which my small MP could fit in AND I took a dustbag.
On one leg, I put my small MP in the dustbag in the bigger carry on bag.
On the other part of my journey, I put it under the seat in front of me in the dustbag.
I was paranoid because it was light colored!