This is seriously disturbing and disgusting. Don't hesitate to say anything, PLEASE. I know it feels awkward, trust me. When I worked at Target, I had an issue with one of the security guys that patrolled the shopping center my store was located in. At first I thought he was being friendly, but then it turned really weird. He was older, in his 60's, and he'd come in and talk to me every night for an extended amount of time. At first, nothing weird, but then one day, he walked up to me and grabbed my hair, which I typically curl, and said, "I really love your curls," and walked away. From that point on, every time he would come in and talk to me (which seemed to ALWAYS be when I was pulling registers, ALONE, and I couldn't leave that cart unattended), he would grab my arm, sometimes really tight and wouldn't let go - or just touch me in some fashion along with giving me weird compliments and it really started to freak me out. So I'd walkie the LOD to come and watch the cart for a few minutes while I "went to the bathroom" or whatever, but he'd still never leave. I was too embarrassed to say anything and I thought they'd think I was being dramatic. Eventually it all became to be too much though, and as soon as he came in, of course while I was pulling cash, I walkied my LOD and asked him to meet me in TSC...I couldn't take another night of it...I broke down in tears and told him everything and he took care of things that night. He told me I should have told him sooner. The perv guy was a few days away from quitting by the time I told though, so luckily I didn't have to deal with his ass again.
Don't even think for half a second that you shouldn't tell your supervisors. This is a serious issue. I'd alert ETL-AP and ETL-HR so they can partner appropriately and confidentially with anyone else who needs to be aware. Don't take it lightly, please.