Play behavior

[Marley]

I've noticed when there are two dogs playing and a third arrives the third starts barking at the two playing dogs. I've also noticed the dogs playing may switch, however the odd dog out is still barking at the playing dogs. All three dogs are friends and play nicely together all the time. Does anybody know what the barking means? Should I be concerned?

[forkin14]

Perhaps it's just an attention seeking bark like "Hey! play with me!" ??

[Marley]

That's what I was thinking, I just want to make sure I'm not missing something.

Thanks