Instructions Don't Lie

While I was giving the bathroom a good scrub, I noticed that our shower curtain wasn't looking so good. Even though the instructions said "Dry Clean Only", I thought "eh, it looks like cotton, gentle machine wash should be fine". I pull it out and it looks fabulous! Nice bright white. I hang it dry to be on the safe side and voila, it looks perfect! Then I hang it back up in the bathroom...notice anything off?
It shrunk! It lost inches on all four sides! We will continue to use it for now since it still works (it just looks funny) but I will be searching for our new one over the next few days.