My kitties are strictly indoor - no street smarts among them. So no cat flaps on the doors. But I do suspect them of ordering pizza while I'm gone and hiding the boxes under the deck.
Update - vet calls this afternoon with results of lab work - you guessed it - the cat is fine. I'm a wreck.
Like h_t's dog, Goldie had an "unadoptable" medical condition - a congenital heart defect & murmur - you'd never know from her behavior there was anything wrong with her. Once a year we take her to the university veterinary teaching hospital in Raleigh for a full cardiac workup - just like a human workup -- EKG, echo-cardiogram, X-rays, etc. Six years and going strong!