It was beautiful after seasoning, until I added some oil. Why?

So I seasoned my first Lodge cast iron pan today. It came out perfect (only one layer, did't look much different than the original pan, though).

Before storing, I applied some oil to the back of the pan. And it became clearly uneven. I tried to wipe out the oil, but it was the same. You can see it is now different to the cooking surface, which I have not applied more oil after seasoning.

Why did this happen? Should I just ignore it and do another round of seasoning?

I plan to wash it with soap to clean it. But I doubt that will help. Any idea please?

Thank you.