mystery jewelry

When I got home and checked my mail earlier this evening, I found a small, bubble-wrap package addressed to me, with no return address except a business in Vietnam, declared value: $2. I opened it, and it was a pendant with two hearts, one in black, shiny stone and one in silver open work, on a chain just barely big enough to fit my neck. Upon further examination, the customs declaration had been signed by someone calling himself Ken on the 29th.

I have no idea who might have sent that to me or why. The necklace is OK, especially for the money, but not the sort of thing I would ever have gotten for myself. Do I have a stalker? Is it a thank you gift for something I didn't think was that big a deal? I haven't signed up to be a secret Santa, therefore I shouldn't have one, and it's early for that sort of thing anyway. The only Kens I can think of are a childhood friend and a fellow at work whom I've known for years.

ETA: Ken Shulman, the director of Lambert House? But I haven't done anything unusual there for years.