Hmm, I would actually probably get that checked out. Baby acne usually doesn't start until about 2-3 weeks after birth as your hormones start to clear out of his body. It would be unlikely to happen at just a day old and it's usually mostly on the face and not anywhere else. They can sometimes get a bacterial infection that comes up as little whitehead like spots, which isn't baby acne but might look similar, which might be something that needs treating. Do you have a midwife coming to see you? If so, I would ask her to have a look at it? If not, yes, I might be inclined to let a doctor take a look at it as it could be a rash or infection of some sort.