I see that too and my system is Chrome, Window 10

omg that Pixpet is older than my parents lol

1/1/1970 is the Unix Epoch. This is a strange error considering usually this kind of thing happens with timezone issues, but as far as I can tell hatches are probably handled entirely on the server in server time.. The only timezone translation should be from server timezone to the viewing system's timezone. However, I'm clearly seeing 1/1/1970 as well and other users are seeing it too, which means something happened to the actual data for the pixpet.

My shot in the dark would be something prevented the server from accessing the current time properly at the time of the hatch, or there's been some form of data corruption in the database that hasn't affected anything else(?).

Me 3!

Update: Found another user with an Ancient One. This time, it's a Troffinch.

Canisqua
Drax
I checked the join date userlist and clicked the top few. I think this is happening to all new user’s starter pets.

This has been starting from I believe starters hatched on October 2nd? Weird that no one has noticed then, do you want to ask some of them to see if it appears to be 1970 on their side?

I've got a old feliphene starter

I would bet pretty heavily that this is the cause, it doesn't have a hatch day because it never hatched so there is no information in that field when registering it to a new account. It explains why the bug started occurring immediately after the release of Adventure.

Fix is to set the hatchday of an "Adventure starter" to the current time on registration.