Rating Question for A03

The rating on my Regarding Tony comic is M for Mature on A03. While there is peen there is no graphic penetration, there is no non-con or even dub-con really.

Someone commented there that I need to change the rating, and I'm honestly not sure if I should. The next step up is E for Explicit which is 'only for adults'.

I would think that the rating of Mature pretty much implies it's only for adults too. (The rating down is Teen.)

Whatdaya think?