I love your colors!
I made 3 of my DGS flannel (from Joanns) rag quilts and after I conpleted each one I put them thru the rinse then dryer 3 times (lots and lots of lint) but they turned out ok. I did tell my DDIL's to wash them by themselves a couple more times due to lint. Also made a flannel kitty rag quilt for DGD and it didn't pill either. Could it be the color combination ? Mine was mostly medium colors. Just a wild guess.