Odd Wild Peruvian Angel behavior

I have recently had a pair form and left them in a ADA 90P alone. I felt as if they were a bit timid and decided to throw a domestic angelfish in to get them eating more and strengthen their bond. After the domestic was added the pair immediately chased and attacked it all over the aquarium non stop. The suspected male then began to what seemed to be marking his territory like a dog would. It began to rub only its papilla on the ends of the leaves and wood surrounding the spawning slate that they've been guarding.

It seemed entirely different than if the angel were to be scraping off of leaves from infection, It only rubbed the papilla as opposed to rubbing the entire side of its body. The pair both were continuously flashing their fins but only the male did this to objects around that area. After the fish was removed this behavior immediately stopped. I was just wondering if there was anyone else who may have seen this sort of behavior ever before. I have never read of this type of "marking" before but found it very interesting.
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