i did google it and i freaked out because the sites were showing pictures of grown men with that problem and i didn't want my baby to be like that when he grew up! then i posted about it on my other forum, which is a nov 06 birthclub, and it turned out to be fairly common there with the other baby boys his age. i'd just never heard of it because it's not something people talk about, you know?
i'd really try not to worry about it. the area around the penis is really called the "fat pad", so it's just fat. i'm assuming even slimmer boys can still have a fattier fat pad and if you can push on it and pop it out, it's probably fine.
i don't know about the size though. it has to be just like everything else, people have different sized noses, hands, ears, whatever. i wouldn't be too concerned over the size. you'll be seeing him naked for a few years more so you'll be able to see if it's growing and looking more "normal". plus as grown men they can all be different sizes, so maybe his will just be on the shorter side.
is he circumsized? it also seems to be much more common for circ'd boys.
oh, and my mom used to bring it up all the time too. she couldn't help but comment every time she changed him and it drove me nuts!