netbios query from remote subnet

If I make a netbios name query lookup against a W7 machine, using linux as the client, and the IP address of the remote machine:

nmblookup -A ip_address

Then, using wireshark on the remote machine, I can see the name query arrive at the remote machine...however since last week the remote machine will not respond if the original request came from a remote subnet.

I can't work out what has changed that would have caused this to star ocurring....any ideas?