Husband seems to be into my sister?

So i have 4 big sisters, im the youngest one. My husband is 7yrs older than me.

Anyways, everytime i talk about one of my sister to him, hed bring up a specific one, and ask about her. Shes the one whos 2 yrs older than me. He always ask me about her, while leaving the rest.

Like, i told him about how my oldest sister is really demanding and controlling to her husband. And he ask me if my other sister, (the one hes into), is like that to her bf.

Shes the only one he says hi and bye to, while the rest he just ignore them. I tend to see him checking her out a lot, w a smile on his face.

One time he told me that his cousin thinks my sisters hot, thats why hes nice to her, and only talks to her. But the way i see it, hes the one being like that, and i think he was just shifting it to his cousin.

He was also into his ex wifes sister, i knew because he had pics of her saved into his phone, when we were separated.

Idk, this makes me feel different about him.