You would have had to have looked from a steeper angle with the 40D, but unless Canon put some sort of physical barrier in place, you would have seen much the same sort of thing. You are looking at the focusing screen using the "wrong" surfaces of the pentaprism, so the image is flopped left-to-right (as it normally would be) but hasn't been righted (the image is flipped top-to-bottom). Because you're using the wrong surfaces, and the prism relies on total internal reflection, eventually the light path will get too close to normal (that is, they will strike the glass surface at too steep an angle) and will pass through the prism surface rather than be reflected, so you'll probably see the image fade out somewhat towards the bottom (well, the lower part, which is actually the top).

If the viewfinder opening is big enough (I don't have a 5D to check it with, but I do have several 35mm film SLRs that all do the same thing), you can move your eye a little higher still and actually see a reflection of your eye (provided it's not pressed up tight against the viewfinder's eye cup and can get some light), since all of the internal surfaces of the pentaprism will reflect by total internal reflection if the light strikes them obliquely enough.

So, yes, it's normal, although it is possible for a camera maker to prevent you from getting an angle of view into the finder that will produce the effect. That would, however, reduce the eyepoint (how far your eye can be from the finder and still see the entire screen) and would probably interfere with the more extreme viewfinder diopters (not everybody can use just the built-in adjustment range).