It's not a stupid question at all.
I would be concerned if I saw this in a kit in a litter of mine, as well. It would tell me things. It would tell me that the kit is probably not as robust as the others. It may be weak or have internal damage (maybe it got stepped on) or internal abnormalities.
I would keep the kit with its siblings, because their heat will help that kit stay warm, and their energy will stimulate him. I would move him to the top of the pile at every opportunity, so that perhaps he will still be there at feeding time. I would pull him out morning and night to check him tummy for fullness.
He may not get as much as the others, but as long as he has a nice little roundness to him, I would let him go it on his own. If his tummy is sunken, then you will have decisions to make. You can supplement him with formula, you can bring him in and see if you can get the doe to feed him while on her back or in a box over him, you can see if he gets his strength back on his own (unlikely), or you can put him down.
Hopefully, he'll make it! :good-luck: