One fine morning if you observe "Event ID : 3759 Database 'something' on SQL Server instance 'someDB' is not empty and does not match current database schema." in your front end servers, then there must something wrong on the build/patch which auto updates on your SharePoint. You can follow the steps below to identify the build number and on which front end server it is missing.
1. Open Central Admin with Admin rights.
2. Click on Update and Migration from the left navigation.
3. Under Upgrade and Patch Management click on Check Product and Patch Installation Status.
4. Hit control + F and type the word Missing.
5. It should show you the front end server name and the build patch which is missing.
For me it was the Security Update for Microsoft SharePoint Foundation 2010 (KB2810059) 64-Bit Edition
Now patch installation involves two processes, one download the security patch and install it. Two run the PSConfig.exe to complete the same. It is important that you run PSConfig.exe or run the SharePoint configuration wizard to complete the patch installation.
Cheers !
