ok thank u ,i was told a while ago that it meant they could be poorly ,but all mine looking well was just worried ,also im not sure if my to girls 6 monthes old are over heating due to new wheel john hopewell its so much faster than the selvic wheel,they just calapes.after being on it on sides and on shelfs /every night i put to coolers from freezer under there bars and cooler slab so im hoping this is helping them ? ,i really dont want to take wheel out as they love it ,any help on this would be great