Process attempted to unlock a resource it does not own
If this is just one time issue and CHECKDB run without any errors and you have good backups, do not bother to investigate it (unless you want to spend time and resources to what is not reproducible).

If you are able to reproduce the issue, then I would recommend you to 


Replicate on a test environment and capture whats going using a
Profiler. 
As a proactive measure, you can probably have an agent job
or powershell job to scan the error log (note that you can put a logic inside Powershell job to only scan from the last time it ended) to look for specific errors like Error: 1203 or Error: 3314 and then fire SQLDIAG to capture what was actually going on when the issue happened.


Let me know if you need any such script and I will be happy to share it.