I don't think it's too young for her to be doing that. I also don't think that she's 'over-bonding' with you, but it isn't something you want to encourage.

I do have a suggestion....in your other post you said that she is starting to bite...if this is the case, then she shouldn't be allowed on your shoulder. The shoulder is a privilege spot and only a bird that has proven they can behave themselves belongs up there. If she decides to nip/bite you while on your shoulder, you could have a serious facial injury.
So, if it were me, I wouldn't allow her on my shoulder until you know you can trust her not to bite you.