<VV> Electrical question...

[Cash Case]

Hi guys-
I have a problem with my '65.  As we all know, there are 2 idiot lights one the dash.  One for Alt/Fan and one for Temp/oil pressure.  The Alt/Fan light is orange and lights when the fan belt breaks, if I understand correctly.  The Temp/Oil pressure is red and lights when the oil pressure is low or the temp rises into the danger zone.  

Normally when I start my car, these lights go right out.  However, in the last few days, I've noticed the Alt/Fan light started to stay on a bit longer than normal.  In the last two days, it has stayed on for five to ten minutes.  I immediately turned the car off the first time this happened and opened the engine cover, assuming I would find a broken or thrown belt.  The belt is fine and I've checked to make sure it is still on each time the light stays on.  The light is bright and not a dim flicker so I know it's not a ground problem.  This is new and I'm baffled as to what it might be.  The belt is new.  When warm, there is about 1 to 1 1/2 inche of play in the belt if I pulled it up and down.  However,  I would think if the belt was lose, it would have behaved this way for the last two months.  This is a new problem.

The battery is not being drained as I drive so the alternator appears to be working.

Anyone have any ideas?
-Cash Case
-'65 Corsa 'Yabba Dabba Doo' style car.