"Block request" is a type of network packet we use - it's a block of the map file used when someone downloads the map to join the game. The message is saying that it got a request for a "block" of the map file from a peer that it isn't actually uploading the map for.
It's nothing to worry about - the person(s) on the other end will time out and reconnect.
If you want to get ahold of me I'm almost always on Discord.