When displaying an action sheet from a bar button, the arrow doesn't always align correctly

So for example, when I call UIActionSheet.ShowFrom(UIBarButtonItem, bool) the sheet displays correctly and the arrow does point to the correct button, but not precisely. Sometimes it's pretty close (see first image) and other times it's pretty off (see second image). I drew in solid backgrounds on these buttons just to verify the underlying image itself was not the issue, and it wasn't. The BarButtonItem and the underlying image used on it are both 16x16 (or 32x32 on retina displays). In places where the action sheet displays on the side of a button (versus above or below) the arrow is always exactly in the middle.

Thoughts?

Thanks! Seth