Accidental streaming to a Denon Heos 7 over the internet?!

[tbee]

Since yesterday I have a Denon Heos 7 at home in my living room. Today I was at work and started spotify on my Android phone, and it found the heos and started playing on it. At home! (My daughter told me about it via chat.) 

Should that be possible at all?! I'm pretty sure I do not want that. Since it is spotify connect at work, I'm posting it here.

[tbee]

From what I find on the internet, this is intended behavior. Why in the world would I want to remote control a speaker? When I'm on the same LAN, yes.