the question is is it an issue or a somehwat odd feature?
yes its disconcerting dont get me wrong and i guess it could be an issue if it did it alot as Pedro's seems to be doing. But there are ways to improve this with the chip or the power commander and the rest is down to how you ride.
An example of something similar with a Honda.... the older fireblades were renowned for having serious tank slappers due to the front end wobbling. You could either live with it or buy a damper! the damper improved things no end, but it could still do it if your rode it hard.