Rheumatoid is always a possibility when you have bilateral multi-joint problems. Osteoarthritis is a wear and tear problem, although sometimes an injury does not have to occur. Maybe your toes are too flexible since you are such a "gumby" anyway.
. Toe stretching might be in order if you are not suffering anything problematic. You might also try soaking your toes in Epsom salts at night. Watch your form as well and rest them.
Another possibility if nothing shows up is that sometimes you can get dropped metatarsal heads and will need to see a chiropractor to get them released.