The weights aren't really reliable. I've had packages from both FedEx and UPS change weights several times on their way to me. Apple may have put 0.4 pounds as the default placeholder, but then when it gets to certain places, they re-weight the package, and then it changes. It's a crap shoot.
Well, according to UPS, the iPhone has gone from Nashville to Wisconsin where it was almost delivered before going back to Louisville and is now presumably on its way back to Wisconsin: