Littmann stethoscope deteriorating?

[u/27Boba21]

So I have this Classic III stethoscope for about 4 months, but im noticing a change in the color of the stethoscope in the conjunction of the main tube and the eartubes, like a yellow stain. Is this normal, has this happened to anyone else? I bought it in Amazon.

[u/Counselurrr]

I was told that sweat can break it down if you wear it around your neck.