Is it normal that i smelt my younger brother’s gf’s knickers while they were asleep?

I’ve been sharing a room with my much younger brother while I’m back home for abit, his girlfriend stayed for 2 nights. They both fell asleep and I got horny, all her stuff was near them so I snuck over and her bag was open so took a little peak, found her used underwear from the day/night before, took them over to my laptop, I smelt them so hard while I stroked my cock, never smelt knickers before, but it was such a sensation to smell pussy and ass while I blew my load. I cleaned up and put the knickers back, just want to know how weird that is, as it was so kinky and felt so naughty, I feel kinda bad