Obstruction question...(long)

[The Max Swineberg 7]

Sorry this is so long, but I'm trying to be as detailed as possible. Umping a slow-pitch softball game, ASA rules. I'm the BU and a buddy is the PU. I did not call the obstruction play, but he overruled me. We argue after the game, friendly of course, and I'm wondering if I was wrong.

Batter/runner is heading for second on a ball she hit to left field. As she rounds second, she bumps into the second baseman. The second baseman had her left foot on the left field side of second base, with her right foot extended....almost looking like a first baseman. She was expecting to get the ball thrown to her, but it was cut off by the shortstop.

I didn't call obstruction because I felt that she left most of the base open, and I usually see player hit the inside of second when heading toward third. There was a bump and the PU called obstruction. I didn't know this until after I called the runner out in a rundown between second and third.

Was this obstruction? I mean, to me I know the baseline is determined by the runner, but the fielder was set and made no attempt to get in the path being on the left field side of the bag with just a foot on it. My buddy said any contact is obstruction.

Who's correct?