When I just bought my Forester, I was looking through the exemptions of the extended warranties. I mentioned it's funny that warranties don't cover catalytic converters. I had also noticed it in my Honda warranty when we had it.
The woman doing the financing mentioned that it was because there was a federal law that says they have to cover it for a certain amount of time. Now, I'm old , so I don't remember the exact details, but it may be covered for 8 years.
If you do some research or ask the dealer, you might be fully covered still for that. I may not seem clear about it, but there are also some articles about it if you google it.