rss isn’t updating

I’ve got a blog webthink.pl and it’s got feed – http://webthink.pl/feed/ (clear & simple) – the problem is that feed isn’t up to date – the newest post isn’t included in rss (I’m not using plugins excluding some cats from feed). WP-Super-Cache is cleared, I haven’t got any additional cache on this host (eaccelerator, memcached, etc).

Any idea how could I solve this problem?