I assume were talking AR15 buffer tube right?
If its new in the wrapper and your not in a hurry I'd send it back.
I'd call the company that made it before you open it and ask them what to do.
That way if they say open it and take a look you can still send it back if there is a problem.
In reality, its a common problem with buffer tubes. Them dang fine threads tick me off. Wish they would have used a coarser thread on them. You could always just thread it in the first time, it will probably self correct. If not file off the offending section.
But call the company that made it first.