When I get in the Tahoe in the morning, even if it's already bright and sunny, the dash lights stay dim for quite a while. Seems like it takes as much as a half hour for the sensor to "wake up" and tell the dash display lights to go to daylight brightness, so I have to brighten them myself while I wait. Shouldn't the sensor get them adjusted in a minute or so? Am I right it's the little glass globe on the top middle of the dash?

 

Are you parked in a garage or a shady area ?
I have noticed that on my 07 even if its sunny out but the sun is somewhat low of an angle or its spotty shade my solar sensor will keep the lights on and dim the IP lights...

 

No, parked outside. I understand when it's dawn and the light isn't direct, but I can be driving at 9 am in sunshine and the lights still take a while to get bright.

 

I did not see any information in my documentation for any calibration of the ambient light sensor.
Might want to make sure its clean, not covered, and is seated properly in the dash...
If you are adventurous, you could try removing it and re-seating the electrical connections to it or consider replacing it...