Bigger in file size doe not mean bigger in screen size. Your Animated one takes up a lot more bandwidth than, for example, JackiesDaisy's bigger-looking image of the cartoon in her signature file.

Your animated one, as Randi mentioned, is 87K! And that doesn't count all the other, smaller graphics you have, all your graphics added together makes up 116k! Her "big" cartoon of Daisy and Perry is only 24K - right around the maximum size we'd like people's signature images to be.

So if you could re-do your signature, that would be great, and consider, as was already said, that some people have slow connections, and when someone has a big signature graphic, it can cause the page to NOT load at all, which we would rather avoid.