Why does my German Spitz Puppy drop her tail when she sees strangers?

I have a german spitz puppy and I let her off leash in this big local playing field and whenever people come close she drops her tail. It's naturaly flipped over her back, but she relaxes it and stares at them. Her ears don't go back, she doesn't try to hide so I don't think shes shy or scared. It's just realy weird, I've never seen another dog do it before & I don't want people thinking she's unfriendly.She's very well socialised and loves meeting people though so I know she's not shy

It is her way of showing you that she is leery of strangers....

i think she is just shy

Dropping the tail could just be a way of informing the stranger that she means no harm, or isn't trying to challenge them. As long as she isn't acting aggressive or shy then I wouldn't worry about it. Dropping the tail isn't necessarily a bad thing as long as her behavior is correct. I'd be more worried about the tail going UP when she sees strangers.