Normal to gently touch myself while staring at my sister in law

This weekend my brother-in-law and sister-in-law were hanging out, drinking and getting high. My sister-in-law and I had been vibing nicely all day. My brother-in-law went to bed. My sister-in-law and I were sitting on different couches. Kind of drunk staring at each other. I am older than her 46 and she is about 33. She seemed to be moving her tank top up to expose her nice flat stomach and she had a very revealing cleavage view. I moved my hand under the covers while staring at her and started to gently stroke myself. She did not seem to mind. I did not take it too far, but she could see my hand lightly moving the blankets and the point of the blanket from my dick. Is this normal?