I agree. I vote "Replace the Battery" and get back to us.

I did NOT say "test the battery" - I don't care HOW old it is, replace the battery and get back to us.

You MIGHT start inspecting the connections in the black box next to the battery, (the little junciton box, not the Control Module box) - but I'm with 100/80 above - sounds like the infamous "My car is doin weird stuff and my battery is only 6 years old" complaint.