Can't tell by those pictures its very minor and caused by an overpolished die.Even if it is,doesn't increase value.
It would be called the Floating Roof. Just a simple overpolished die issue. Nothing really major. Your pictures are not the best.
Is it a floating roof if the outermost edge(s) still is visible? I thought all of the support had to be gone. I never have looked for them nor would collect them, just curious. Jim
As @paddyman98 already stated, it is called the "floating roof" and is due to the die being over polished to keep it in service. Other devices on the coin will look weak or missing, like the designers initials. Fairly common and certainly NAV unless you have a fetish for them.
I have so many of them it ant funny I have the p and the d and the s one there just cool looking that is all people are trying to make a fast doallar and it ant even a error people trying to take people that sounds about right.