Crack in inner dome in subito mini from zio ciro

[Ofrofr]

Hi all
I bought 2 weeks ago brand new oven called subito mini made by zio ciro
After the curing process there was a crack inside the dome the expanding in heat.
The local distributer says its common in refactory ovens like this but I want to get second opinion.
Do I need to insist they replace my oven?
What is a crack that needs replacing my oven?
Thanks a head
Ofrofr