Illegal Trade?

'Splain this one, Lucy.

The Cubs traded Alex Gonzalez at or before 3:00 PM CDT on Saturday. The Cubs game ended at 3:04 PM Saturday with Alex Gonzalez on the field to end the game.

Is that kosher? Doesn't A Gonz have to be off the field as soon as the trade is closed? Or is it that A Gonz has to be off the field ASAP? Are their repercussions? Anyone have any ideas on this?

Bueller?