YES THAT SUCKS. Maybe make a problem and get a replacement or return it and hopefully it has 6.1.2 or less.
Edit: i thought 6.1.3 was out and knew it patches the JB.
If you mean 6.1.2 which I believe you do, you are fine.
Make sure you restore to 6.1.2 and then Cydia should save blobs / connect device to computer and save them with tiny umbrella in case a re-restore method ever comes out for A5+ devices
And let this be a "lesson" for when 6.1.3 actually comes out
The official 6.1.3 hasn't been released to the public yet.
Unless you're on a devs account and installed the 6.1.3 beta.
If that's the case you can still restore to 6.1.2 and then JB it.