re: I need the OB's opinion - was I wrong here?

You are good to go. I run plates for guys like this in my neighborhood. An individual has NO expectation if privacy in regards to a license plate on a public street.

"[A] motorist has no privacy interest in her license plate number." Olabisiomotosho v. City of Houston, 185 F.3d 521, 529 (5th Cir. 1999); accord United States v. Sparks, 37 Fed. Appx. 826, 829 (8th Cir. 2002); Hallstein v. City of Hermosa Beach, 87 Fed. Appx. 17, 19 (9th Cir. 2003).