Just got such email from YC:

Title: Your Y Combinator Application

Hi Bartłomiej and Tomasz, Thanks for applying to YC. We thought your application was promising and would like a bit more time to review it.

We’ll get back to you with a decision within the next month.

There’s nothing you need to do on your end, but if you’d like, you can submit a full update to your application here: https://apply.ycombinator.com/app/edit Thanks, YC

any thoughts on that?