in the last few days i've seen my pleco laying upside down in his cave twice. normally he attatched to the roof of his cave and he looks like he fell off and just decided to lay there.... i am worried that he may be ill or dying. has anyone else seen their pleco acting like this before? he is about 8 inches long and i don't know how old he is. he came in my tank and he was about 5" last year.