Games no longer appear to be using Retina graphics

I just opened up Angry Birds Seasons today and the graphics looked blurrier than usual. I don't know how reliable a screenshot is but here is one I took and you can see it looks blurry. (Also, the image came out at 800x534 pixels, but apparently the Retina display is 960×640.)

I recently upgraded from an iPhone 3G to the 4S and transferred all my settings directly, so I wondered if the games were perhaps still trying to use the non-Retina display. However, I hadn't noticed any problems with the games until today, and another game I've downloaded since the upgrade also doesn't look quite right today.

What could be the problem here?

It seems the Angry Birds Seasons you're trying to play, doesn't have retina support. If you take a look at the customer reviews, you'll see some people complaining about the lack of retina support.

And if you're used to an iPhone 3G screen and make the switch to the gorgeous retina display, you'll see a huge difference. But so far, no retina support for Angry Birds Seasons.

UPDATE:
It looks like Rovio is adding Retina support to his latest creation (Space), so I'm guessing it won't be too long when the others games will support the Retina display too.

(Or maybe the opposite, they don't add Retina support in order to convince the users to buy the latest Rovio products...)