I-35W Bridge in Orange

Back in September, I was out for a ride along the river and was surprised to see the I-35W bridge lit up in orange.  It has been blue every other time I saw it (click here for pics in blue).  I know they light the bridge in different colors for different occasions and reasons.  This was the first time I had actually seen it done but I have no idea what the reason was this day (9/1/2012).