Pulled Over For Expired Registration

I live in Texas. I was pulled over tonight for an expired registration. Upon further investigation it was discovered that my inspection sticker was expired and my address was incorrect on my license (since I never bothered to change it when I moved last year). I was issued a citation for an expired registration and given a verbal "warning for the other two violations." I asked the officer how she made the discovery and she explained that she arbitrarily "runs" each license plate she passes. Since I knew I wasn’t speeding and it was dark I knew she must have done this, as there was no other explanation for the stop. If I am not mistaken, in my city, all I will need to do is register the vehicle, get the inspection and then show proof to the court. At which point the citations will be dismissed with a 10 dollar "processing fee." I haven’t been pulled over in quite some time, so I'm really starting to steam the more I think about this stop. What constitutes a valid stop? If I were walking down the street I wouldn’t expect to have my ID "run" so why would my plate be run? I'm probably just venting here, but I'd really love to take this to court. The vehicle was my wife’s, which I know doesn’t make a whole lot of difference, but if it were my friends car, would I really be expected to validate that the vehicle was registered and inspected before operating it? Why would this not apply to my wife’s vehicle?

http://trafficlaw.itags.org/q_traffic-law_164650.html