I am working my way through a bolt of warm and natural. I never pre wash fabric or batting (but i do use 2 to 4 dye catchers). I like the shrinkage I get but I am quilting it pretty tightly on my pfaff hobby grand quilter. I have to remind my self to make the top bigger so when I do get shrinkage, it will still fit the bed. the old fashioned crinkle makes my day, but the quilt is still straight and flat.
The rewetting and blocking idea sounds good, but i would not fret too much. only you will know that the quilt is a little wonky. the receiver will love it is warm and cuddly.