There's this video I've seen on youtube recently regarding a shadow figure. The people recording felt threatened just by starring at it. So I would assume your intuition will tell you whether it's a harmful shadow figure or not. However, you were'nt aware of it being there so you might of had a different reaction if you knew it wasn't your husband. I would assume not all of them are bad, but I could be mistaken. I just find it strange a shadow being would linger inside a home one time and never to return. Perhaps there's some history behind your house, maybe a murder?