Tailwheel Crosswind Landing

I am a long term lurker and have a question regarding landing tailwheel
airplanes in a crosswind. I have about 250 hours in a Piper PA-12 Super
Cruiser. The other day during a very routine crosswind landing I
started heading for the weeds faster than I new what to do.

I had a fairly gentle cross wind from the left. I had cancelled out all
sideways drift by lowering my left wing and aligned the plane with the
runway with right rudder. At touchdown, everything seemed perfect. That
is when all hell broke loose. As soon as I touched down, I started a
very fast turn to the right. At one point I was headed right between
two runway light. As I was deciding that "between" was not a bad place
to be, I finally managed to straighten everything out and managed to
stay on the runway.

In talking to my mechanic as soon as I touched down (I was sure there
was a mechanical problem), he figured that with all of the right rudder
needed to keep things straight, that my tailwheel just sent me to the
right once it touched down.

My question is, what was really going on here? Should my tailwheel
have released (castored) when I touched down? Your thoughts are greatly
appreciated.

Thanks.

Tom