My wife has been peeking at me from around corners and behind furniture. It's gone from annoying to terrifying

My wife "Lynn" and I have been together for six years and married for 11 months. Our entire history together has been very normal and never once have I noticed any strange behavior. She is the love of my life. I was always so comfortable with her that I never even had to turn around to see her when I heard her walk up behind me. I could just reach behind me and we would hold hands without me looking. We knew each other's habits and expressions so much that it often felt like we were the same person. After being together for six years, I thought I knew her better than I knew myself. That was until about three months ago.<br><br>It started with just catching glimpses of her out of the corner of my eye. I would turn and see her just walking around the house doing normal things. After a week or two passed I started to think she was just stalking behind me on purpose as a joke. She would walk quietly behind me and I would turn around to find her smiling and going about her business as if she was just roaming the house. It was annoying but I found it a little cute. I would ask her why she was doing all this creeping, but she would tell me she wasn't and that I was just seeing things. After a few weeks of continuous "seeing things" I started to think I actually was seeing things. I became so used to it that life went on as normal and she was still the love of my life.