The rear sight base should be spring loaded and if you twist it clockwise, it should return to the same position shown in your pic. Perfectly normal. If you want it to be square, I would suggest having it pinned by White Oak. There are some other companies that can pin the rear sight also.
I bought one on Amazon and it came that way. I called the manufacturer and they sent one to replace it...free and immediately It is spring loaded(sort of) but should be straight. They told me it was not something I could fix. to be fair it was not expensive and I got it with a short rail attachment for the top to attached a Red dot scope. It completed my AR Build and I am pleased so far.
It this is new send it back. Otherwise i can offer nothing of value to help...