I agree with MadQuilter -
"Sorry, but I do not understand the idea of seams coming apart. Don't you check the seams when you sew the pieces together? "
I hardly ever prewash fabric - though some vintage pieces probably have been before I get them - and I never wash wall hangings. I do fluff them wish a damp towel and a dryer sheet. Baby quilts, lap quilts and bed quilts do get washed. We all love the crinklies! All that handquilting had better show to its best advantage!