A while ago, I noticed that a few of the hatchlings in Sylesti Nurturing were actually Adolescents when I went to their pages, though it wasn't giving me any sort of error when I nurtured them. I've started getting errors ("This pet is too old to be nurtured") about it now. The pets appear as Hatchlings, but are actually adolescents. ^^

Can you provide an example or screenshot?

Is it possible that your nurture or your profile view was the last bit to make them become an Adolescent?

Hm... All of the adolescents' maturities seem to be 216 (from their URLs), and checking their profiles before nurturing them shows that they are already adolescent.

Here's one of the pets in question:
Profile (before nurturing)
She's the middle one in the top row here

When I click to nurture her, it allows me to select an action, and then gives me the error "This pet is too old to be nurtured!".

@Blue,

Profile Views add Maturity up until they are Adolescents.

So if they are at 215 and 9/10 for the profile maturity views. If you search the Hatchery they'll come up as a Hatchling. If you then click the profile, the profile view can kick them up to 216 and make them an Adolescent.

Then when you go to nurture them, it will say they are too old b/c they are no longer a Hatchling.

If you're finding that once you know a pet already is an Adolescent and it keeps popping back up, then that would indicate that there's probably something wrong.

But from what it sounds like, your profile view is causing them to become an Adolescent.

I figured it was probably something like that, though after getting over a dozen of them I wasn't so sure. Thanks, Krin! ^^