Apple iPhone X silicone case dirty

I purchased the peach iPhone X silicone case last weekend and it already is starting to have discoloration. I don’t wear jeans, I don’t put it in my pockets so the discoloration isn’t from fabric. For $39, it’s just ridiculous. I talked to Apple support and they told me to take it to the nearest Apple store for them to deal with. However, the nearest Apple store is over an hour away and by the time I make time to go there I’m not sure if a warranty will still be in place. Any advice?