I made this account yesterday and moved my Clydesdales here from another account.

I logged in today to see that I earned two achievements: 50k Baby Born & 100k Baby Born.

However the youngest horse on this account is 4th generation mare that is currently 6 years old. So I don't know if there's an age limit on the "baby" point achievements, so thought I would point it out just in case it was a bug. XD

Nope, not a bug! It'll do that.