speedo problems!

I have a 95 eagle talon tsi and I'm having issues. The clutch was replaced right before I purchased the car. When the car was sold to me I noticed that when I started the car the speedometer would jump to 45 at idle. When I start to drive it moves like it should so if I'm doing 10 then it reads 55. My mileage is not affected either. So if I drive 100 mile it is realy driving 100 miles. Is there something broken? What should I do?