Silly me, oh silly me.
I dumped the cheese sauce in - and it turned a lovely shade of brown. Hmmm, I think. This doesn't seem right. And it's certainly not smelling all that great. Very suspicious now that I remember how my mom likes to get lots of dry goods and then sometimes forgets she's gotten them, I dig the box out of the trash and check the date. November. Of 1988.
I dumped the offending contents down the garbage disposal, ran it, and am in the process of disinfecting the pot. Ick. Ick. Ick.
I retire now with a lovely, fresh peanutbutter sandwich.