At least twice it has said that I have a cat in my cart after I reload the page, but I didn’t click “Add to Cart”. However, they have been imaginary cats.
OK, this is very strange. I again simply reloaded the Pumpkin Spice cat page – had not clicked “Add to Cart” – it said that I had a cat in my cart, and this time I was able to check out.
Presumably I have actually bought a Pumpkin Spice cat through some quirk in the system. If not, oh well. 🙂