Force Touch trackpad issue

I bought a Macbook Pro 16 M4 Pro yesterday and after one day of use I wanted to clean my trackpad with a cloth with alcohol and I saw that after wiping it a vertical line appeared which after a while disappeared but was slightly visible against the light. I called Apple Support who said that the warranty does not cover the cosmetics of the device. The authorized store that sold it to me said that it was normal and that it was leftovers from assembly. Is this true? Photo and video links below - sorry for my english, i used translator.

https://i.imgur.com/HwMxkh5.jpeg

https://www.youtube.com/watch?v=T1vkDQL9sOs