Does it happen practically every time or less often? Does it seem like it is not springing back from the start position? If so, my first attempt would be to just remove and lube it.
Take tumbler out, use screwdriver (plus holding key close so the security chip communicates) to turn ignition switch. If that seems to work fine, I'd examine tumbler for wear areas and consider replacement. If all else fails, put replacement in and see if it resolves the problem. If not then I'd get the switch too.
Does anyone know how much trouble it is to rekey these? Is it similar to rekeying a standard door knob, or more work involved? Sometimes when I rekey doorknobs, I don't even need a pin kit because the pins from the old knob are practically like new still, so I just transfer over the old pins to the new cylinder. In this case it looks like replacement cylinder kits, come with (not pins but...) keying plates so you just pick the right height combination and sequence? I'd look for a youtube video.
If you have a lot of weight on your key chain, I'd consider keeping the vehicle keys separate to cut down on the weight strain on it. If there was wear, I'd also add some lube to the wear area on the replacement.
