Many babies wake three or four times a night for the first year,especially dring the first 6 months. yoru son sounds totally normal and healthy to me!
sounds like you had a very unusually solid sleeping first baby, so of course it makes you concerned about your second baby, who sleeps, actually, more like most babies.
I highly suggest getting the Dr. Sears baby book, even though you already have had a baby.
Every baby is different, and this reference book is easy to read, very helpful about he range of baby behaviors, whats normal, whats not, what we can do for them in all kinds of different situations.
this way, as your second baby continues to grow and perhaps be quite different that the first, you will have a really great and easy to read reference book to check.
C.