One of my adult European pond tortoises, Emys orbicularis, just lost one of its scutes,like a big finger nail, from its carapace. It's not like when my RES does it and it's a pale outer leaf that comes off leaving the pattern beneath. This seems to be the entire patterned scute leaving a dull black one underneath. I've had E.orbicularis for years and never had any shedding at all. Is this normal or a worry?