My husky ,Caspian displays some unusual behavior when meeting new dogs or new people. When he meets someone new dog or person the hair on his back stands strait up like a cat. I used to think he was scared and not social, but his behavior does not match that. Even though his hair stands up he still acts playful or just doesn't mind at all.

Does anyone else dog do this with his hair, just curious what it means.

That's his hackles, Koda always has them up near other dogs he doesn't know even when he is being friendly and playful. It means they are on high alert.. if he does it and still acts fine, then I wouldn't worry about it. I only worry about hackles on dogs that only raise them when getting nasty.

The hair on their back that raises/stands up is called their hackles . And it is an involuntary action that can show aggression, fear or excitement. Sounds to me like Caspian is just in a really excited state/alert

Unless he is baring his teeth/growling with hackles raised and showing other signs of discomfort/aggression I wouldn't put much thought into it .

ETA: Apparently Heather beat me to it

Kale does that when meeting new dogs too, and when he gets excited when we play in the backyard lol I've gotten so much crap from ppl at dog parks because of his hackles being up during play that I don't take him anymore. Last time I went was 4 weeks ago and the other owner left grumbling about an aggressive dog...

My two do this on a regular basis when playing with each other etc...

Ginger raises her hackles when playing with Storm! Or when she's excited...or when she's on alert.
I don't think I've ever seen Storm's hackles up...

Like Heather said, worry when they're nasty with hackles up...