Here is a screen-capture of the <i>new</i> page: http://i.imgur.com/M5Kwn.png<p>As you can see, one of my submissions has the orange star while the other one does not have it. Furthermore, there is an upvote button on that item too.<p>Out of curiosity I clicked the upvote button and it looks like the vote registered and now the item shows the orange star.
Your initial vote as the submitter didn't get registered. Several things happen when a story is submitted. I don't make them atomic because nothing serious breaks if they don't all happen. So if the thread spawned by the http request dies (because the server restarted, or it times out due to a spike in load), some may happen and not others.
Not a bug, just how HN works. Same thing happens if you make a comment.<p>Notice the id variable in the query string, its going to be the id of the orange-starred submission. You can change it to the ID of another item on that page, and the star will "move" there.<p>Its very handy on comment pages, because it lets you see your comment in context very easily.<p>Edit: I didn't mean this to be offensive. Is the downvoting because of inaccuracy or tone?
Some time ago I had a problem that, intuitively, felt similar. An internal inconsistency showing itself as an oddity. PG replied that it happened very shortly before the system restarted itself - it had got into a funny state, was doing the best it could, gave up, and restarted.<p>This feels similar, but I have no specific knowledge of the internals, and speak without authority.