Wearing my [M] facemask in her panties

So, I have a huge fetish for sniffing used panties, and my gf knows this. She’s caught me many times and even brings fresh ones to me before she jumps in the shower.
So, given that it’s now mandatory to wear masks in shops in Wales, I (semi-jokingly) asked her if she’d wear my mask in her panties for a day, expecting her to tell me to fuck off. But to my surprise, she smirked, called me filthy and held her hand out. I handed it over and watched her put it inside her panties, with the inside directly on her cute little pussy.
That was three days ago. The last two days have been bliss. I jump at the chance of popping to the shop just to get a whiff of her amazing scent all while unsuspecting strangers go about their day. I hardly took it off yesterday, wearing it around the house. But it’s the thought of no one else knowing, or maybe someone smelling it too without them knowing where it’s coming from!