I'd send it back...
However, if you care less, simply file off the rust and apply a tiny amount of grease t the area. As lol-tastic as it would be, that's not a good area to get rust. HOWEVER, any damage will take a while (5+ years at least for even cracking, let alone failure) to manifest,
Test me: I'm a materials scientist. I even have a PhD in materials science, too.
But I would personally send it back. If I had just shelled out to tool up, I'd want it perfect, too.