Stretched preview image when using Ti.Media.showCamera together with an overlay

When opening the camera with Ti.Media.showCamera and setting an overlay for it, then the shown preview image is stretched to fill the screen, which results in an image with incorrect aspect ratio.

So this looks wrong:

var overlay = Titanium.UI.createView();
Titanium.Media.showCamera({
    overlay: overlay
});

And this looks correct:

Titanium.Media.showCamera();

Is my code wrong or how can i use showCamera together with an overlay and seeing a correct preview image?

Thanks in advance, Florian

PS: I see this on an iPhone5s using SDK 3.2.0 on iOS 7.0.4.