Is it legal to get pulled over for no reason?

I merged onto the highway, just happen to be in front of a trooper. I seen him behind me, kept his distance at first then came in the left lane, looked at me then got behind me and turned his lights on. First question he asked me, he said my name and asked if it was me. I said yes. He asked why are I am driving under suspension. I told him I was teaching my girl to drive stick. He then did a triple look at my inspection and asked for registration and insurance. He couldn't find anything else to fine me. He gave me a court day for driving under suspension. He said it's my 6th time, that's it.. I got pulled over for nothing. It seemed he looked in my car to see if I matched the picture on his computer. Now, I'm looking at jail time supposedly for 6th offense.