I created a new page. The icon for the page in the page bar was set with the first token I placed on the page, as normal. Later I deleted that image from my library. Now the page icon shows as a broken image and nothing I do changes that. This is an annoyance right now but as I go through and clean up my image library I suspect a lot more pages will suffer the same fate and it will make it hard to find the right page with a quick glance.