If you need to use those 2 squares that shrank up, I would recommend washing everything. Otherwise, it's up to you how you want your finished quilt to be used/laundered. Personally, I'm like Ginger & will pre-wash absolutely everything (yes! even pre-cuts). I've never had a pre-cut shrink by a whole inch. I wash in cold with Tide Free & dry on low heat, which is what I recommend as washing instructions to my recipients.
If the 9" will really throw you off, I'd just go ahead & piece/quilt the thing & worry about the bleeding/shrinkage later. I've had to work with blocks that were 1/8" off due to my cutting errors & having to constantly adjust my measurements across the entire quilt was a bit of a pain, so I get why you would not want to work with an odd numbered block. Your fabric will shrink up some in the quilting process & will shrink again when it's washed/dried. As long as you're okay with that & calculate for some shrinkage in the end (probably not 2"/block, but maybe as much as 1"/block), just have some Shout Color Catchers on hand for the washing process & know that the worst case scenario if the Color Catchers aren't strong enough, you may need to re-wash with Synthropol.
Good luck!