Try to understand what caused the gap... e.g. is it because the parts were not clamped together while riveting (meaning there may also be a gap where the closest rivets are located) or is it because the bearing is too wide to fit in the recessed gap?
I had the exact same issue, which I caught before riveting. Your brackets are not perfectly flat, plain and simple. I spent literally hours getting them as flat as I could, and still ended up with a small gap. There is no way around drilling out rivets and flattening the pieces more. That is, if it needs to be fixed. To answer that question, you'll talk to Van's support.
I did have the same result with actually the very first action on my rv12 kit
VAN’s support told me that I probably pressed t hard, but they considered safe to leave it this way