Keys work in ignition but not door locks

Over a year after buying a great '02 Tahoe LT, I came to a startling conclusion. I've always used the remote to unlock the doors and disarm the factory "security system". Recently, I was going on a fishing trip and thought I'd better bring a spare key in case I dropped my remote in the lake. Much to my surprise, the keys all worked in the ignition but not in the doors. This sucks. If the battery ever died, how would I get into my truck other than calling AAA? Even if they got me into the truck, would it even start with the security system not disarmed? It's the factory system, not aftermarket. What would be the least expensive way to deal with this? thanks in advance!

Ignition doesn't match for some reason ASSuming the door cylinders match each other. Ask the dealer to run the code and compare the cut numbers to the key that works the ignition, a good key guy could tell you if the key matches or not. The factory security will allow the truck to start if the system is going off assuming the key works. If the key that works the ignition does not match the GM code I'd get a new ignition cylinder and have it coded to the GM number ASSuming they would then all match.