Hi!
I think it is a manufacturing problem. My S key also popped out after a few weeks. Thankfully they replaced the whole keyboard under warranty, but they did tell me that they could not replace individual keys.
After replacing the whole keyboard, the S key popped out again after a few weeks. This time I was away from the country so could not get it fixed under warranty again.
I want to get it fixed now, has anyone been able to fix the individual key or is replacing the whole keyboard necessary? Honestly I think the metal hooks are now a bit bent so I'm scared to even try buying a key kit...but it would beat paying 150$+ for a keyboard replacement to have it pop out again soon after.