It may be a cacheing issue. See Wikipedia
Basically when you computer goes off to find a web page it remembers some of it so that it will load quicker. You wont notice it usually but if you change a page and visit it again sometimes it will not bother to actually look for new content.
You can try pressing "Ctrl and F5" together while you are on the page. This will reload the page for you.
If that doesn't work you can clear your cache in "tools" then "options" but it may affect other things.
If "Ctrl and F5" doesn't work just wait and it should appear.