Senile Road Rage?

I left work yesterday at 5 to make a 6pm mountain bike ride in Pleasanton.  On my way through the side streets of Fremont, I pulled up to a stop light alongside an elderly couple in a white Cadillac.  Just behind them was a 20-something-impatient, honking and yelling at them to pull forward so he could make a right hand turn.  I saw this, and thought to myself: just let them be man, they're like 80!

The light turns green, and as I wait for people to make left turns in front of me, the white Cadillac rolls on down Peralta and the huge vehicle that had spent several minutes honking at them made his right turn.

When I finally catch up to the elderly couple they're going about 30mph max down this single lane road.  No biggie though, I know in ? mile or so that it splits into two lanes.  And when it does, I accelerate a bit and move on my them.

This is where we both come to a stop at Paseo Padre.  Ahead of us is an immediate merge, back from 2 lanes to 1.  I don't think anything of this though, because based on how the couple were driving on Peralta, I'll move by them and be able to merge left with no problem at all.

The light turns green.  I gently accelerate.  I switch to 2nd gear. 

And the elderly man driving the Cadillac on my left?  He floors it!

I don't know what's going on.  He's old.  He was driving 15 mph below the speed limit just a few seconds ago.  And now I have 150 yards to make my merge.

He's still a ? length behind me and I can't convince myself that he's intentionally flooring it.  So I keep accelerating in a controlled manner ? surely if I go just a bit faster I'll be able to move in front of him.

To the left, I see his car violently jerk as his automatic transmission engages and upshifts.  I apply a little more pressure to the gas pedal.

Still, I'm no farther in front of him and I have just a few more seconds to go before the lane ends on me completely.  I look in my rear view mirror.  Every car that was with us at the stop light is just now getting through the intersection.  What's more, there's a huge cloud of brown dust following behind us in our mad drag race down Peralta.

At this point, I say fuck it and let him pull away.  I slide in behind him and 20 seconds later he pulls into the turn lane to make a left hand turn.  I look over at him utterly dumbfounded at what just happened. 

I'm still not sure what set him off but I wonder if he thought I was the one honking at him at the first stop light.  If so, I'm chalking it down to road rage by senility.