We don't know how much warning Apple gave them. To be fair, two months to update such beastly products is really nothing, especially when you have to change core functionality (like on-screen rendering in an image-creation tool...). I'd say 4 to 6 months would be an acceptable turnaround time for the most important products.
Compare with Microsoft, which simply won't support retina "for the time being"...
(Edit: that's Gimp and Acorn in the screenshot, respectively, in case you weren't clear what was going on.)