> I was just nervous that it might mean nothing or they’d say “well you got AppleCare+ and spoke to a support agent the same day, clearly you’re trying to get one over on us.”

Nah. Dust inside the camera assembly with no other apparent structural damage is clearly manufacturer defect. In practicality, Apple sells on both volume and price point so they’ll likely just eat the cost as a surprise and delight unless it’s just blatantly obvious. And you didn’t actually do anything.

Just go in and tell them what’s up. “hey, I’ve had this phone a minute. Always been careful and it lives on its case. But I think I have dust inside the camera. This should be covered under warranty?” Bring your receipt or proof of purchase of you have it just in case, but this shouldn’t prove a hassle.