Yes it seems quite common in chocolates. It was discussed a while ago on the site if you look it u poo you will find more info on it.
I started a thread on this for my Marley last year: https://thelabradorforum.com/threads/white-ring-around-the-tail.19087/ At around one year the white pretty much disappeared although just recently I noticed a few white hairs in that same spot.
Hi we have a chunky chocolate Labrador nearly a yr and he too has quite a few white hairs in patches seems a bit strange when he is so young
Our 5 year old black lab has a white patch on his chest that he was born with. People usually think he's not purebred, but he is and the breeder said it's just something they see every so often. Both black males in his little had small white patches. We love it...makes him unique.