66,000 miles, transmission issuses already?

Having said that ive notice a few strange naks with the transmission, Occassionally on slightly heavier braking,
when coming to a stop the car feels like it downshifts hard into first ,
problem is it doesnt happen all the time and will very rarely happen when braking normally,
has anyone else had this problem or know what the cause or solution might be?
Any help will be greatly appreciated







