Yup, this "soft start" is normal operation. The wheel senses the blade and then quickly jumps up to full speed. There's some fancy engineering reason for this; basically, it's to make the transition from not touching to touching the blade as smooth as possible. This protects the components inside of the sharpener and the initial contact point on the blade from extra wear.
*If it bounces, try lowering the height by a setting or two. Are you sharpening toe to the right? If not, try that direction. One of those two should help you out. If you happen to have a higher than normal desired contact point you're trying to hit, you may have to live with a bit of bouncing. If it were too violent, the sharpener would shut down from an overcurrent error.