Is Requirements Traceability Matrix (RTM) a configurable item (CI) or not? Do we need to maintain its version history?
This is a question you really have to answer for yourself by first addressing some more basic questions. How critical is the RTM to the success of your project, organization, and business? What do you use the RTM for? Tracing requirements? Verifying and validating requirements? Regression testing? What value to you, the project, and the organization is the change history of the RTM? If you identify strong business needs for the RTM, then the answer to original question will become obvious.
From my perspective, the RTM is not a CI per se as it is a tool for managing your requirements and not necessarily a product component. But it is a very important, if not essential tool, and maintaining its change history could be necessary for project and organizational success.