What's caused this?

[Pint]

I forgot to post this up when it happened, but when I was giving my new car a good clean with a range of new products I had bought I had something happen that I have never seen before.

It happened after using either car pros iron x or tar x - I used one first then fully rinsed the car then applied the second and this appeared ( just can't remember which product was done first)

I panicked and didn't really know what to do but attacked it with some rejuvenate which eventually got it looking like this.

 

[Knuckles]

Just looks like the tar remover working, did it dry on?

 

[Pint]

I didn't let it dry. There were other areas that it had been longer and were fine. It was my first time using the products so wasn't sure if I had done something wrong.