ROFL, no, my Roundabout was gifted to a friend when my kiddo outgrew it last month.
My king had those same markings, worn blue fabric on the one side only, stains on the straps... I was 90% or more sure it was mine when I was looking at it. Of course, many were made, but that particular print wasn't easy to find-- I got mine in NY.
I actually emailed the seller immediately, and innocently (unless somehow my email addy was in the car somewhere?) asked how old it was, how far from downtown she was since I work downtown, etc. Curious to see if I get any response. You could email her, too, though, and let her think she'll have a bidding war on her hands! (actually, this may work since my x may have been involved in the theft and he does know my email... hmm... )
I had it registered with Britax, wonder if they'd release the serial numbers (or if the registration ever got recorded properly by them)