Welcome Mitch! I too am new, but Holi-Crap....this IS an Addiction! I jumped into the deep end of the pool buying a Mark 23 two years ago, but I still marvel at the guys on here with a PAGE list of all the HK toys they own!
As for the VP-9, you've already heard it from a bunch of guys here, totally normal if mag-slammed hard. From pistol to pistol there are a bunch of factors that will affect that condition. Tension/age of the slidelock lever spring - depth/height of the slide stop notch - tension/age of the recoil spring, and of course....if you HE-MAN the mag change. I tend to agree with Lamont that it's a benefit for a competent shooter. In the case of the g.f., just give her ample warning and let her grow into LARA CROFT !
Mike