Some times 600 errors are not real errors but, version of products, compatibility issues etc. They don't remove the old features of the product, these desupported product features will be embedded some where in the latest versions and gives problems due to conflicts.

I have been told by Oracle to ignore, if its one time incident and database is up and running with no problems or issues.

If database is working fine and you don't have any issues, there may not be problem. All you need to do is confirm with Oracle that there is no problem.

Bottom line it has to reported to Oracle for peace of mind.