That's so sad! But you know, that sort of thing is quite common. I have ghost-cats (anyone who owns a cat knows about ghost-cats). I will be lying in bed and actually feel my (long-deceased) cat Klunk hop up on the bed, mince up to lie next to my knee, and curl up to sleep. From habit I put my hand down to pet her, and there's nothing there (not even my very alive cat, Piccolo). Madness!
When I was in Japan I was struck with a sudden and very extreme case of rheumatoid arthritis (which, for the uninitiated, is an auto-immune disease, and not related to my then not-particularly-advanced age
). I was literally crippled by the pain and inflammation, and couldn't get up out of bed (one of my co-workers came in every day to cook for me!). One day I was half-asleep (or maybe all the way asleep) and I could feel my mom beside me, rubbing my left arm to help ease the pain; and it did help, and the pain was greatly reduced. Then I woke up and realised she wasn't there at all, and I think I cried for an hour, because of the pain and the homesickness and wanting my mom to be there to rub my arm for real.