I'm 41, and when I'd lost too much weight, I noticed the fine lines appeared almost out of nowhere. Now that I'm at a healthier weight (I was slightly underweight so opposite of you), the fat has plumped up my skin nicely.
No one seems to guess my age correctly. They always seem quite shocked when I tell them, lol. I will say that I've taken care of my skin almost fastidiously since I was a young teenager: Oil of Olay, eye cream, sunglasses to prevent crow's feet, sunscreen and not lying out in the sun so maybe that has something to do with it as well. Not to insinuate that you didn't, obviously.
I don't know if that exactly helps you or not but that's my two cents.
Congrats on the weight loss too!