nope it's cradle cap-and it can be cradle cap until they're 6!! my little sister had the most insane cradle cap you ever saw until she was 5 and it just went away by itself. my own 19 month old dd has it, from the time she was about 6 mo. i've tried olive oil, dandruff shampoo (which does get a bit of it off, but is so strong i dont like to use it on her often), baby oil, berts bees apricot oil, peeling it off, brushing it off, nothing really has made a difference in it.
instead of continuing to drive her nuts peeling her head i just dont mess with it. unless it starts to pull off on its own, and i gently brush it out. i noticed the spots where i peeled it off seemed a little raw, owwww, so that made me stop peeling. you can't see it unless her hair is pulled back off of it, and it doesnt seem to really bother her. maybe there's some biological reason that it's there. i heard there was an "old wives tale" (hate that term) that babies with cradle cap were certain to live thru infancy (grim, but those were tough times to be a baby when that was said!) dunno...
i use either weleda calendula soap or j&j lavender shampoo on her hair now. neither seems to help or hurt.
i don't see how hair length would or could have any bearing on it, since it's the scalp that's affected, not the actual hair.
i know, great advice