Rendering bug when sliding slowly and navbar is gone

Hi, I am experiencing the following bug:

If my navbar is scrolled away and I am slowling sliding to the previous page in stack, the view of the navigationbar behaves weird:
http://findpenguins.com/img/AMScrollingNavbar-Bug.png

In this case, there is a tabbar attached to the navbar, but the same phenomenon is also happening without a tabbar, when simply opening a new screen while navbar is gone (just too quickly to take a screenshot).

Just wanted to let you know, also to find out if you guys are experiencing the same problem.

Tobi