The problem is not that someone postet the link - the problem is that the original link/post was hidden and exactly 1 hour later someone else postet it.
That's strange. You can write to hn@ycombinator.com and ask why your submission is [dead]. Maybe it got caught in some spam filter, was unblocked and then somebody else got lucky.
Thanks for the tip. But even then "somebody else got lucky" would be a very very big coincidence - the project is roughly 3 months old and wasn't mentioned recently. That someone decides - exactly at the same time - to share the link is very strange.