I think that there were 10 days in between the weight checks (Friday- the Second Monday) so it was over a pound and half per day. I am definitely willing to guess that he may be over-fed, especially since DH was giving an extra ~3 ounces per day.
The point I was trying to make about the very rapid gain-still, very nearly two ounces a day rather than the average of one-is that some good portion of that gain must have been from the breast. Besides the 3 ounces from your husband, how much total in supplements was/is baby getting?