What happened to my arm?

It has been over a week now and I really have no interesting dreams lately. That makes me wonder because I remember having more vivid dreams in the past but nothing worth writing about has come up as of recent. A few nights ago when I was asleep, I looked at my left forearm and noticed it was insanely deformed. It caught me in shock. I looked away, blinked, and then stared at my arm again to see if my eyes were playing tricks on me. Luckily, my arm looked fine after the second glance. Of course, this is just like a few seconds of dreaming out of several hours of dreams that I fail to remember but for some reason this episode stuck out the most. I wonder what that means.