The only place I see that is right where its doing the maint plan on the db - database integrity. And it failed on the db in question. Do you know does the db maint plan where it checks data integrity put the db in single user mode? If I look at the text file that the maint plan created when it got to the db in question it had the following:
7] Database PBDSS: Check Data and Index Linkage...
[Microsoft SQL-DMO (ODBC SQLState: 42000)] Error 924: [Microsoft][ODBC SQL Server Driver][SQL Server]Database 'PBDSS' is already open and can only have one user at a time.
[Microsoft][ODBC SQL Server Driver][SQL Server]Only the owner of object 'dtproperties' can run DBCC CHECKTABLE on it.
[Microsoft][ODBC SQL Server Driver][SQL Server]Database 'PBDSS' is already open and can only have one user at a time.
[Microsoft][ODBC SQL Server Driver][SQL Server]DBCC execution completed. If DBCC printed error messages, contact your system administrator.
The following errors were found:
[Microsoft][ODBC SQL Server Driver][SQL Server]Database 'PBDSS' is already open and can only have one user at a time.
[Microsoft][ODBC SQL Server Driver][SQL Server]Only the owner of object 'dtproperties' can run DBCC CHECKTABLE on it.
[Microsoft][ODBC SQL Server Driver][SQL Server]Database 'PBDSS' is already open and can only have one user at a time.
[Microsoft][ODBC SQL Server Driver][SQL Server]DBCC execution completed. If DBCC printed error messages, contact your system administrator.
** Execution Time: 0 hrs, 8 mins, 57 secs **
It actually repeated this message multiple times its like it kept trying for a bit. So to me it looks like it was in single mode before it got here. But not quite positive.