Thanks. It's definitely rust.

I generally change the filters on schedule, but didn't plan on the car sitting for so long without being run, so I just didn't realize this would pop up...I replaced the filters and have spares in the trunk...we're going to drive it today and have a look at the filters when we get back. It ran fine before they were changed, btw, but runs much better now. It's also been washed/waxed

Since it is our "3rd" car we were getting it ready to sell it in favor of motorcycles, but after driving it around the past couple of days I think we have decided to keep it. Motorcycles can wait...it's refreshing to drive the 300 after commuting in my slowpoke 240 all week.