If you are concerned, I would naturally contact your vet and ask him or her to take a look over. However, what you dont know is that the probable reason is that the cats are knackered. You mentioned that you and your husband have a donut shop - wish we had them in the UK - however, these little bundles of fluff are being mini terrorists when you leave the house. They wait and watch all night and as soon as you wake, they put on the sleep bit as if have been up all night. The door closes and the cats go nuts for hours, tearing up the suite, down the curtains, pruning your house plants, in the sink, then have a great roll around - have a snack and then do it all again. When you get in, the cats are that wrecked, they have to sleep - for these are furry terrorists who have no fear and they munch a huge amount of donuts when you are out!
Just keep smiling, give em loads of love as kittens are such wonderful ways of starting cats! Same advice we were given when my wife gave birth to our son - babies are such wonderful ways of staring people.
And if worried - the VET word is the best