Very strange Apple TV benefit.

I've noticed that on 2 occasions my A-TV has connected to the 'net and one time it downloaded an update. All on its own! The last thing it was connected to was my iMac using an ethernet cable. When this 'net connection has taken place my computer had been put to Sleep, disconnected from the 'net and its internal Airport Extreme is turned off. Today I was suddenly able to download some movie trailers to watch. Is it connecting to some nearby wireless network even though it hasn't been set up for that?? Very strange.