Wife told me I masturbate in my sleep

19 male, 160lbs 5’9-5’10. She says last night she woke up to me “masturbating” but i literally have no recollection of anything. She’s been in a grumpy mood all day and when i finally broke her to fess up she told me she woke up to me jerking off. According to her “my shorts were down and I was actively doing it”. I didn’t even have a dream or anything last night. Just nothing like usual. I only call BS because I’ve spent the last 6 months sleeping in racks and bunks next to multiple dudes (I’m in the military) and not one time have I ever woken up with my shorts down or anyone tell me I’ve done that. Why would I do it in the bed with my wife but not when I’m alone for 6 months? It makes no sense