Weird graphical artifacts in iPad app

[csnplt]

I'm having some problems presenting a modal view controller within a popover (using UIModalPresentationCurrentContext).

Here's what my popover looks like before I present the modal view:



Here's what the modal view looks like within the popover:



After dismissing the popover, here's what I get (notice the artifact at the bottom of the popover):



Any ideas as to how I can fix this? Using another popover isn't really an option now, but it's what I was using before trying this. (Though I wasn't rejected, Apple "recommended" fixing this after reviewing my last update).

Thanks for any ideas.