Exchange 2010 Event ID 1

Hello all,

I just noticed today that a few active exchange DB's failed over to their passive copy. While trying to figure out what happen, I've come across this error log that keeps popping up:

Log Name:      Microsoft-Exchange-MailboxDatabaseFailureItems/Operational
Source:        Microsoft-Exchange-MailboxDatabaseFailureItems
Date:          12/8/2012 10:37:57 AM
Event ID:      1
Task Category: Store
Level:         Information
Keywords:      
User:          SYSTEM
Computer:     Domain.com
Description:
Failure Item (Namespace=1, Tag=16, Database=CN=Mailbox Database 1284537266\0ADEL:4b88d962-5d85-4b78-ba05-995447d6fceb,CN=Deleted Objects,CN=Configuration,DC=DOMAIN,DC=com, Instance=Mailbox Database 1284537266)
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Microsoft-Exchange-MailboxDatabaseFailureItems" Guid="{08E893EA-4C11-4FFF-A737-99B9EEDEE4F4}" />
    <EventID>1</EventID>
    <Version>0</Version>
    <Level>4</Level>
    <Task>1</Task>
    <Opcode>0</Opcode>
    <Keywords>0x8000000000000000</Keywords>
    <TimeCreated SystemTime="2012-11-08T16:37:57.174331700Z" />
    <EventRecordID>1</EventRecordID>
    <Correlation />
    <Execution ProcessID="5520" ThreadID="6780" />
    <Channel>Microsoft-Exchange-MailboxDatabaseFailureItems/Operational</Channel>
    <Computer>Domain.com</Computer>
    <Security UserID="S-1-5-18" />
  </System>
  <UserData>
    <EventXML xmlns:auto-ns2="http://schemas.microsoft.com/win/2004/08/events" xmlns="myNs">
      <Version>1</Version>
      <Namespace>1</Namespace>
      <Tag>16</Tag>
      <DatabaseGuid>{4B88D962-5D85-4B78-BA05-995447D6FCEB}</DatabaseGuid>
      <DatabaseInstanceName>Mailbox Database 1284537266</DatabaseInstanceName>
      <Component>Store</Component>
      <IOErrorIsSpecified>false</IOErrorIsSpecified>
      <NotificationEventIsSpecified>false</NotificationEventIsSpecified>
      <IOError>
        <Category>0</Category>
        <FileName>
        </FileName>
        <Offset>0</Offset>
        <Size>0</Size>
      </IOError>
      <NotificationEvent>
        <EventID>0</EventID>
        <ParameterBufferSize>0</ParameterBufferSize>
        <ParameterBuffer>
        </ParameterBuffer>
      </NotificationEvent>
    </EventXML>
  </UserData>
</Event>

Any idea what this means and how to resolve it? 

Thanks