Maybe, maybe not.
If the diameter is too small because of a fault on my end, then certainly I will make it right.
If the diameter is too small because that is how you specified it, then the responsibility is on your shoulders, and the question becomes is it cost effective to recut the mold vs. ordering a new mold? Yes, I can probably recut it, though there is always some risk involved, and I would have to charge you for my labor. If you want to go that route then mail the mold back to me and I'll let you know what I come up with.
One way for you to enlarge the diameter is to coat the bullet with powder coat or Hi-Tek, if you are not already doing so. Powder coating generally increases the diameter 0.002".