Growing up in St Louis it sure will be strange to see lambert without any twa aircraft flying overhead, but I guess that day is rapidly approaching.
I would guess that the reduced flight schedules makes it 1) a heck of a lot easier to rotate the aircraft out of service for paint jobs, and 2) the reduced maintenance from less flight hours on each plane means more hanger time/space and maintenance crews time available for painting and such. Plus AA should want to take advantage of TWA's young fleet by making sure it isn't looking old with the old colors, the paint job makes them look that much newer.