Oh, cool! I don't think (speaking as one on the fringes) that there's any problem with acknowledging. As long as you don't threaten to sue, people are happy.

In fact, I know of one author who cut a few scenes from a novel manuscript and posted them to AO3 as official fan-fiction by the canon author, as in "Here, these didn't fit the finished story, but they're entertaining in themselves. Enjoy my orphaned darlings!"