It's not uncommon around the Black Cat area for them to pull that crap of saying they've observed your car. They tried doing that to a friend of mine who was visiting for the first time into DC. Bored cops with nothing better to do (yes cops do this, not parking enforcement) so they're sitting in the Parks and Recs lots and running tags.
While I have lived in DC for quite some time, I finally caved in to become a resident. I had had enough of beating the system getting ROSA exemption status and having meetings with Parking Enforcement to show the new hires that certain spots are exempt from the 2-hour resident rule.