You done good, Rob, my son - you done good! :-) Sitting in at a welcoming and tolerant session - with the right attitude, which you have - is a great way to learn a part of the tradition. And, because the people aren't always exactly the same from month to month, there's always something new to listen to and enjoy.

If you do this sort of thing regularly, it's great training for the ear, and you can eventually - to a certain extent - anticipate melody and probable chords. Sitting and just listening through the first chorus of a strange tune is also recommended. Alan and I go to a monthly singaround where one participant, an experienced but slightly insensitive performer, just digs right in on guitar when people are playing - even if the chords are different and even if he's never heard it before. He's a nice fellow and an old acquaintance, but he's a little over-confident. Gets right up Al's nose sometimes!