If you do a View Source, it is just an <img src="url..."> tag to an image. I don't think IH would mind since the data should not flow through their server. Your browser fetches directly from the URL specified.
Someone with a dial-up access might object, though... Perhaps its time for a [large] warning on the header :-).
Also, when the original URL for the image is no longer valid, you will see the following:
- kc
p.s. here's an idea, for premium membership, IH should offer some storage for you to store a small picture to use as a signature :-).