Hairline crack around most of the Apple Watch Series 3 Cellular inside

I was only just today I noticed this crack that goes along 3/4 of my Apple Watch inside. I researched and found that it resembled a hairline crack. I was playing European Handball when after I realised that it had a long crack inside it. I also noticed a couple of days ago when I took my watch off charge in the morning it was warm. Could it be a swollen battery or could it be the impact or catching and throwing a handball? What should I do with it? Go to the nearest Apple store so they can check it out and tell me what's wrong? Or would it alright to leave how it is and if I do does anyone know if it'll get worse?

Hopefully I can get an answer ASAP