A 2002 starter is about 18 years old and definitely could be the problem. They don't last forever. And it could be the starting circuit; battery, wiring. Make absolutely certain that your batteries are up to snuff, load tested, battery cable terminals are bright, shiney, and tight on both ends - including the grounds, and the starter electrical terminals are nice and clean and tight also. The starter lives in an environment that can be problematic. Check your voltage at the starter and also on the S terminal to make sure your starter is 'seeing' the voltage of the battery, check from the battery+ terminal (not the battery cable) to the starter terminal (not the battery cable attached to the starter). If electrical is good ,i.e. actual battery voltage vs what arrives at the starter, it is time for a starter.
2008 Silverado LT, CCLB, Edge Insight CTS
2009 Arctic Fox 29-5T, Silver Fox Edition, Onan 3600 LPG generator