As this is a V880, I would hope that the server is still under a support contract with Sun, in which case yes it would be a good idea to open a support case with them. Even if the dimms do not need replaced they can log the events for you which helps your support on this server in the future, should you get further issues.
But, back to business. What I would do is to pass the server through maximum diagnostics a few times and check the outputs for reported dimm errors.
Other than that you might like to give us a little bit more information, such as the following:
1. The errors from the /var/adm/messages file
2. The output from prtdiag -v
3. An indication of if the server is crashing with these errors and if so if any crash dumps are being created.