While not fully aware of the exact FKT for Gannett, Andy Dorias ran from the Elkhart T.H. to the summit and back in 12h45m55s on August 26, 2011. See below. While slightly slower than Bakwin's FKT, this is the fastest time for the longer (42 miles?) Elkhart - Titicomb Basin - Dinwoody Pass - Gooseneck Glacier route. Dorias' ascent time of 6h30m was an overall ascent record for the peak. His trip report is here.
This last August I ran/hiked/scrambled Gannett from the Elkhart Park TH and made it to the summit in 6 hrs and 30 min after talking with my pops (who was camping in Titcomb Basin for 5-10 min) and chatting with a guided party at the base of the Gooseneck. Total round trip time was 12:45:55. I wasn't aware of the actual record time but that's irrelevant anyway since your run was from a different TH. Maybe a record from Elkhart?
What a beautiful mountain and run...