Is this bunny a runt or peanut?

[Sseckel]

So I have a litter of 7 Holland Lop kits about 5 days old. There were 9 in the litter and 2 were still born. Of the surviving 7 one little guy is quite a lot smaller than the others, which are all about the same size and easily double this little guy. He seems to be well proportioned albeit smaller but his head and ears seem normal and he moves around the nest very well, his legs all seem strong with good motor control. He has had a full belly each morning and evening so I know he is getting to nurse at least some. But he is so tiny I don't want to get attached if he is a peanut.
I keep my 3 does in a colony. 2 are older (10+) and haven't taken to a breeding in years. The other is a year old and the mother of this litter. One of the older does started removing her belly fur though once these were born she wasn't with the buck ever (at least not that I know of, my kids do the chores sometimes to help me out so not entirely impossible). Is it possible she would have delivered in the other does nest? Or would one of them have moved/adopted it? I've used other does to foster but I've never had one do it on their own.
Pic is below, I will get a better one of his head and body in the morning but this should help with the size difference. The kit on the left is the average size of the others the black kit on the right is the one I am worried about.

 

[_-Captain BRM-_]

Oh yes, I'd say that's a peanut. I do mini's- haven't had much Holland experience.
I keep my lops in a colony setting as well. It's isn't unheard of for the other does to pitch in with fur, or even go into milk when they see kits, even if they weren't bred or haven't been in contact with a buck.