The number of idiots out there running WiFi without any sort of encryption or other restrictions that would keep freeloaders from using them is just plain scary.
UBoB, if you are not using some sort of encryption and/or MAC address filtering, MasonM or anyone else that wanted to could still piggyback on your network for free. While he might not (and probably wouldn't) get access to your systems, he would be able to go surfing the net for just about anything he wanted to, including kiddie pr0n, or anything else (not that he's inclined to do that, just that it would be possible). (Edited to note UBoB's comments about his wireless network not being able to access the internet -- that is a good thing, but better still is using WEP or WPA and even better still is using some sort of hardware address filtering -- MAC address filtering -- to prevent unauthorized access).
So many people buy and/or hook up wireless equipment any more and very few really take the time to enable any sort of protection/restrictions. When the FBI comes knocking wondering why you've been cruising certain sites, or have downloaded articles on bomb making and such you can truly claim ignorance, but they'll spend hours going over your systems with a fine tooth comb because you were running your router open to the world.
It doesn't surprise me that MasonM was easily able to find such a system out there, like I said there are tons of them. And I am not accusing MasonM of doing anything untoward on the systems he is accessing the net from, but if people did things right the only free WiFi would be city provided, or perhaps libraries or locations like that. You wouldn't find it anywhere that didn't intend to provide it for you.
Meanwhile, MasonM, have fun and be happy about getting some net access. It is nice to find it in unexpected places.