Birthdate Question

So, I had a foal born yesterday {9/27/16}, but his birthdate is listed as (9/22/16). Is this a bug or no? (9/22) would have been the day I bred my mare. Sorry if the answer is listed elsewhere

It looks like horse's birth dates are technically the day they are conceived, because I know it lists that a stallion has a foal the day you breed a mare to it, regardless of whether the foal has been born yet or not, so my only guess would be that their birth dates are just the day they are conceived.