Is it normal that i get turned on when my cat licks his butt?

I love my cat very much and the love he gives me in return is ten fold. He's like a bestfriend to me. He's also my baby. He's always there for me and he comforts me in bad times and he LOVES to cuddle and play.
However, whenever he starts to groom himself, and then he goes to start licking his butt area, I get like a very intense erection. There have been many times where I've pre-came watching my cat do this. I feel really weird typing this but I don't know why this is. I'm not attracted to cats, it's just when he spreads his legs and puts them in the air and licks his ass clean I just get REALLY sexually aroused... And if he starts to lick ME afterwards I can't control my erection and I just start orgasming. Are there any reasons for this? I know this sounds ridiculous but please don't be sarcastic or rude, I want helpful answers.