Agreed on taking it to the dealer while it is under warranty. Probably something is loose that needs to be tightened.
If it wasn't still under warranty, you might want to consider an aftermarket shifter, which should be a lot tighter than the factory one, and the installation of the new shifter should fix any installation problems.
If it wasn't still under warranty, you might want to consider an aftermarket shifter, which should be a lot tighter than the factory one, and the installation of the new shifter should fix any installation problems.