Did I ruin my cast iron?

I was drying it out and as it was cooling it the darker spot started browning and flaking off, left in those spots is what you see. It’s an older cast iron that my mom gave to me for just moving but I’m still learning how to care for it.

I was drying it out and as it was cooling it the darker spot started browning and flaking off, left in those spots is what you see. It’s an older cast iron that my mom gave to me for just moving but I’m still learning how to care for it.