It's normal, all smarts do it to some degree!

I've also asked some engineers about this and the consensus is that while the speedometer will read fast, the odometer should be actual.
Fun fact: Federal law says speedometers must be accurate within
+/- 5 mph of actual
at 50 mph. Most people misquote the law as meaning you can't design a speedometer that runs more than 5 mph faster than actual but it actually means
plus or minus. From the federal perspective, an automaker can release a car that reads 50 mph when it's actually going 53 mph and it would be federally legal. Though I'm sure that would open up the automaker to lawsuits over speedometer accuracy. Thus, many automakers tune their speedometers to run faster than actual.
Many automakers like GM, Toyota, and Ford will all read dead on. My 1997 International 3800 also reads dead on at any speed. Of course, that runs the risk of your speedometer running slow should you upgrade to taller tires.