I believe that each TPMS sensor has a small battery built into it. Kind of like a watch battery.
If you have the original sensors it would be reasonable to suspect that one or more of these have failed after 8 years.
Now I don't know that this condition (failed sensor) would give you this message or would show up as just one of the tires not reporting a reading at all.
When I have tire issues I go to the nearest Sears Auto store and have them check it. They, and I am sure others, have a tool that can be used to reset each individual tire sensor but you may need to talk to someone there that is familiar with it. The last time it took a manager to explain to the tire techs how to use it.