Egg laid WAY too early?

[Rin]

Last night I went to lock in my flock of 3 month old Easter eggers and discovered a shell-less/softshell double yolker had been laid on the ground where it had burst open(everything looked proper and "normal" inside like a hen that had been laying for weeks).

Now that it's morning I took a good look at all of my birds and none of them looks any more "ready" than the other and all sources say 5 or more months is normal, I only just now started my birds on finisher - I'm so confused what to make of this. I've had birds start on soft/no shell eggs before without issue but this is way too young for any of that, right?

 

[AlienChick]

I also had one of my EE's lay early.
She only laid one or two eggs then took a 2-week break.

 

[Rin]

I also had one of my EE's lay early.
She only laid one or two eggs then took a 2-week break.

Thank you, this is good to know. I was worried whoever the culprit was going to die soon as I couldn't find /anything/ about birds laying as early as 3 months. No one seems weak or listless or anything today, it's almost as if the egg fell from the sky. XD

EDIT: Just letting you know apparently the adult guinea I've had for months now is a hen... ...I don't even... I had other guineas but she was WAY BIGGER and made cockerel noises. :|