You'll find this one eventually on 2010 - you'll see the warning appear in the Central Admin Health monitor. It is a bit vauge as to what the real issue is but you can find the details on the Microsoft Site:
What they are not saying is actually why this occurs; I've had this happen on test systems that were only running for a few days. The result is that monitoring will not work properly (i.e. the usage reports). The quick fix is via SharePoint's PowerShell - open that and do the following step.
NOTE: You must be an Admin to do this - check out the Add-SPShellAdmin comand.
Step 1 - Get the GUID of the Service Application
Managed Metadata ... Managed Metadata ... 9dbca54d-59e9-4f2d-bfe7-2ece94635750
Web Analytics Ser... Web Analytics Ser... 30e00364-c80b-4091-b2fc-04ed10ac0dae
Excel Service 1 Excel Services Ap... 7a290551-7d57-471a-87d8-7c7f6c6b424f
Notice the Web Analytics service - copy the GUID in the ID Column.
Step 2 - Turn on Data Trimming on the Reporting Service
> Set-SPWebAnalyticsServiceApplication -Identity <GUID> -EnableDataTrimming
(replace <GUID> with the GUID you copied above - NOTE: if you only have one Analytics Service, you can omit the GUID)
Give if a few minutes to let the SPTimer job kick then return to the Health Monitor, click the message and select Re-analyze Now - message should go away!