Yes. Was the same in the neo hybrid. I'd say the case was on the phone for 4/5 months.
And yes. The mark was permanent. Completely ruined (to me anyway) an otherwise flawless phone. No matter what I tried it wouldn't come off.
Ever since I've used a back protector on my phones just to be careful. I don't know why it happened. It hasn't happened since. But then the newer phones are different material so it could be that. I imagine I was incredibly unlucky.
I've avoided SGP cases since but I like the capsule. But I'm torn about ordering it due to that previous issue.
I'm waiting for sketch cases and the candyshell grip and they're what I've used on my last two iPhones.
Can you post a few pics of the capsule if you don't mind? Just so I can see what it's like in the flesh so to speak.
I can under 2 conditions:
1. You tell me how to do that ha (took pictures with the phone so they're not the best quality)
2. You're okay with phone pictures.