Question about tune and going from High to low altitude

Hello everyone,
I'm going to have the car tuned by a guy here in Colorado that does great tunes for making power here at a mile high, and I have a question. I'm also taking a trip to Omaha, NE late in the summer and I wanted to know if the tune would adjust to the altitude (via the computer adjusting) or if it would be running really lean then because it was tuned at 5,200 ft or so and there would be much more oxygen in Omaha then here. Or am I being an idiot? I love feeling how it runs at lower altitude without a tune and I hope it would be even better with it, but want to make sure I can use it at the lower altitude. Thanks everybody!

Yeah...I'm N/A. I figured I was being an idiot but had to ask anyway. He actually uses Diablo (don't know of any tuner in Colorado that had a good rep that uses SCT) but I don't think that really matters. Thanks for the replies...