Yea I just took mine in yesterday for this, noticed it when I was installing my dogbone insert. At first the tech said what I said 'That sum bitch is cracked!"
A few bays down there was a Golf TSI in the air, it had the same "seam" as we started to refer to it as. However mine, like yours, is opened up noticeably more than it was on the Golf TSI. I will keep an eye on it, but seeing this makes me more comfortable. Glad you got a picture, my phone is garbage and couldn't focus up in that cavity.
I might get ambitious enough one day and weld it just because. If anything it is a point for corrosion to start.