Anything is possible and I can't tell you that you do or don' have a problem with your limbs because you've had problems before, but I can tell you that I've had similar type sounds several times that came from my TAC15i, but it never turned out to be a limb problem.
When I would get these sounds once in a great while, I always figured that whatever was causing the sounds, I couldn't find any cracks or d-lamination problems, so I would just keep shooting without a break.
My assumption was that I had a years warranty from the manufacturer, so I would push the crossbow until something actually broke, otherwise it wasn't really a problem. I put over 3,000 shots on my crossbow and still haven't had any breakdowns.
I've worn out an arrow rest or two and replaced my string stop bumpers once, but otherwise I've had no real problems with the crossbow.
Regards,
Jon