The stretching looks normal, but that's an awfully big rat. I believe that Adam said he feeds small rats to his colony.

You might consider switching to a weekly feeding schedule of one small/medium rat a week.

I have two adult females that are both rat eaters. I buy what the pet store classifies as small rats, they each get one a week. Now yesterday, I did tell the girl "I want the largest of the smalls" (they are priced differently for small/med/large). I think because I come in there each week, she actually gave me two mediums at a small price, because these guys were 1 1/2 x as big as the ones I normally get.

But in any case, after getting those ratties home, I would have preferred smaller ones, but the snakes didn't care, though it did take them a little longer to eat.