I had a play called from a different playbook than what I had selected in my Game Plan settings. When are the Game Plan conditions checked in the game?

Which Game Plan to use is determined at the end of the last play.  Each play in the play-by-play shows when the actual play was snapped, so the game plan may be selected well before the time you see next to the play.

For instance, if you have it set to switch game plans when 3 minutes or less, and a play ends at the 3:05 mark, the next play may be snapped under 3 minutes, but will be called from the previous game plan because the game plan to use was selected at 3:05 (the end of the previous play).  Please keep this in consideration when setting your Offensive and Defensive Game Planning settings.