I got a ticket in Fl for having it vertical on a swing arm bracket. I don't think the cop would have pulled me over for the tag itself, but I took a left hand turn through an intersection, VERY aggressively. I htink he just got me for whatever he could. Most states have regs about the plate being horizontal at the rear of the bike with a light and must be visible from 50 - 100 ft behind.
After my fix it ticket, I figured it would be better just to move my Tag again...... But a agree with the above posts, I don't think a cop would pull you over for that alone.....