Just got permanent crowns yesterday. Flossed today and pulled out glue? Could I have broken crown already? (Photos)

I went and got a total of 5 porcelain crowns (w metal) completed yesterday. My results were pretty great, in my opinion, until I messed them up by flossing. I flossed tonight by pulling out, not down, and pulled out a tiny bit of what I thought was glue. Now, I'm paranoid because it appears that the area is darker and I'm worried that i made some hole/gap or chipped something? These are my first crowns. I'm paranoid but I spent a lot of money and pain - don't want to ignore a problem!