I have a very nice RBTA, it's been in my tank for a few months.... It is in great health, nice color and opens up big everyday.... It never truly deflates... Maybe once or twice in the past few months.... But the top "disk" has been creasing for a few days now.... Is this a sign of it starting to split? I always though that it splits from the foot first.... It is right in line with its mouth but it's only creasing on one side?