Today during my ride I hit a bump on the trail and heard an unusually loud "crack" sound from the rear of my Kestrel Talon. It was alarming enough to make me wonder if I had cracked the frame somewhere, but after stopping and a quick inspection I found no frame problems. I took a closer look at home and the frame is intact, however when I bounce the rear wheel on the ground it seems like the chain is looser than normal and is striking the lower chain stay which appears to be what's causing the "cracking" sound.
I've never torn apart my Ultegra rear derailleur so I'm unfamiliar with its internal components. Is it possible a spring of some sort gave out? The bike shifts OK up and down the gears.
Thanks in advance for any advice.