No reason to feel stupid.
I would spray some gun oil down the barrel and run a patch down the barrel and see what you have. If the bore is fouled it will come out black. If it comes out red then you have some rust and may want to look into pulling the breach plug if this model has one.
If it is a small amount of red I would clean it with a bore brush of the proper size and then the bucket of very hot water. Then use the oil of your choice to coat the barrel, like I said I have been using "Bore Butter", I can't remember who makes it right now. Just give it a quick cleaning before you shoot.
They are fun to shoot and they make lots of smoke.