Chrome Surprise: Zoom Settings are Remembered by Domain

I just now investigated an interesting phenomenon. Opening an image in a new tab in Google Chrome from my web e-mail interface and then zooming it resulted in the main mail tab also being zoomed when I went back to it. I also have noticed the zoom level changing while the web app loads (i.e. when I log in). That's kind of strange, but there is a reasonable explanation.

It appears that Google Chrome stores zoom levels based on the page's domain (the part between the protocol and the slash after the TLD), not the URL or tab. The image I opened was hosted on the same site as the web app, so zooming it changed my zoom level for the entire domain. The log-in screen redirects me through a couple pages on different subdomains, so different stored zoom levels came into play.