Getting System.InsufficientMemoryException intermittently, mostly in async plug-ins

In one of the CRM Online orgs I'm working with, the following exception has appeared a few times today:

Unhandled Exception: System.ServiceModel.FaultException`1
[[Microsoft.Xrm.Sdk.OrganizationServiceFault, Microsoft.Xrm.Sdk, Version=8.0.0.0, 
Culture=neutral, PublicKeyToken=31bf3856ad364e35]]: 
System.InsufficientMemoryException:

I searched the forum and it doesn't appear that anyone else has run into this lately. But I thought I'd check just in case.

The plug-in where it failed most recently is registered post-operation async. All it's doing is setting the Worked By of a queue item to the new owner of an opportunity. So the plug-in isn't consuming an abnormal amount of memory, or at least it shouldn't be.

Anyway, if you run into this and know the cause please let me know. I'm guessing that I'll need to open a support case on this.  :(