It's probably less anything Lapis is doing and more the moonlight to blame. Or maybe Peridot is just that easy to please. Mostly she was just really happy that Lapis is putting up with this level of closeness, and now that her more beastly side is taking over that's translating into something much more extreme. Because dragons don't do anything in moderation, apparently.

Not dissuaded in the least, she takes to nuzzling the nape of her bonded's neck instead, and. Very briefly. Brushes her snout against her gem. Definitely by accident! She has a very big nose.