I have eaten left over biscuits and gravy many times over, but I always store the biscuits separate in a ziploc bag, gravy in the fridge. Pop the biscuit in the toaster, microwave a little of the gravy and it's as good as fresh made (almost). Did you make your own gravy? It's incredibly easy and tastes far better than any pre made stuff. Quick version, cook sausage and crumble in a pan, do not drain, make a little well in the middle of the pan so you can get the flour on the pan surface and add a little butter and 2-3 tbsp of flour, mix that and slightly brown it like making a roux, then mix it throughout the sausage crumbles, stir in milk, let it simmer until it gets thick. I have tried a couple times to make my own biscuits but I suck at it. They're never flaky. So I just used canned ones. Biscuits are deceptively difficult.