Weird feeling

So I'm going back to work tonight in 2 weeks. I've been on vacation. As I'm getting my keys to my car, I suddenly felt overwhelmed and nervous. I don't know why. I'm not nervous to go to work or see my coworkers, so I don't know why I feel nervous.  As I was walking down the stairs my legs felt shaky. Is this normal ? It seems like some type of anxiety I've never had before