Our children are 8.5 years apart in age, so DD came along a good 3+ years after DS had weaned himself. He did say one day that we should "raise this one the way you raised me." Sweet child, as if he was already raised!
I'm tying to think how I might've handled that fondness if he had still been that focussed on them. Maybe allow some cuddling (Thinking of the "you don't need a pillow if you've got your mom" line from the song "Use a Napkin, Not Your Mom"), but ask him to keep his hands down? Sounds like he approves of the fact that the new baby will be being breastfed. That might be approval rather than incipient jealousy being expressed there. Every once in a while, kids can be pretty darned wise.
OTOH, that's no guarantee that he won't also have such feelings once he sees baby nursing. I wouldn't try to predict, but play it, state it to him such that of course it's good that baby is nursing, and that he nursed too for as long as he needed too. Leave him space to step into that big brother supporting baby's need to nurse if that's the route he looks to be heading.