Well, it could be one of two other things. One, it could be that the ignition switch is bad. Two, it could be that the instrument cluster is going bad.
On this series of vehicles, the ignition switch is known to go bad. The question is not if it will go bad, but when will it go bad. Many of us carry a spare ignition switch for when the time comes. Here is a nice write up on how to replace the ignition switch:
www.trailvoy.com
Diagnosis of a bad ignition switch is by exclusion - ruling everything else out, or by the weirdness factor - why is it my dash lights only work on the third Thursday after a full moon and my radio thinks it has become a scanner whenever I hicup.
One other cause - a light bulb on the instrument cluster is brighter than it should be and it is kind of like "bleed over", but this only happens when the instrument panel is illuminated.
Here is some interesting reading:
www.trailvoy.com
On this series of vehicles, the ignition switch is known to go bad. The question is not if it will go bad, but when will it go bad. Many of us carry a spare ignition switch for when the time comes. Here is a nice write up on how to replace the ignition switch:

How to replace your ignition switch (pics)
Okay, I replaced my ignition switch yesterday. I was nervous, I had read numerous posts about this, but some of them conflicted, and I wasn’t sure what I was getting myself into. I haven’t done a whole lot of work on newer car systems, although I did replace the stepper motors on my Envoy a...
Diagnosis of a bad ignition switch is by exclusion - ruling everything else out, or by the weirdness factor - why is it my dash lights only work on the third Thursday after a full moon and my radio thinks it has become a scanner whenever I hicup.
One other cause - a light bulb on the instrument cluster is brighter than it should be and it is kind of like "bleed over", but this only happens when the instrument panel is illuminated.
Here is some interesting reading:

Random Dim Battery Light
I get a random dim battery light. It shows up randomly and almost always goes away after a couple hours of driving. If I do not drive until the light goes completely away, it will stay on dim when the vehicle is off. I have done no electrical mods to my vehicle. Advance Auto Parts ran the...