Is scaling of the scalp a sign of infection?

Yes. I was originally taught that this was a dry skin condition. I have seen many treatments come and go. The current theory is that this is a fungal infection. It frequently gets better when treated with a mild antifungal cream, such as lotriminaf. Talk with your provider about how often and for how long.
No. Your baby may have a common benign newborn condition called "cradle cap". It is a kind of baby dandruff caused by overactive oily glands on the scalp. Try applying a small amount of baby oil or olive oil to the scalp, then using a soft baby brush to gently remove the flakes, and then wash your baby's hair. If that does not do the trick, contact your doctor as there are alternative treatments.