Brown area on plastron - 2mo old Leopard tortoise

[Neckbone]

Hello!
I’ve started noticing some brown discoloration on my 2 month old Leopard tortoise on his lower plastron. I think the linear markings are normal growth lines, but I’m concerned about the brown smudginess near the bottom. Does this look normal / okay? I want to make sure he is healthy. Other than water soaks, should I also be bathing/cleaning or wiping him with a sponge or gentle toothbrush? Or is that unnecessary? Thanks for your help!
!

 

[wellington]

Nothing looks out of the ordinary to me. It's likely just changing of color which will happen a lot as they grow or its staining from the substrate.