When you sign back in, you should have a spool file of your joblog.
Work with All Spooled Files
Type options, press Enter.
1=Send 2=Change 3=Hold 4=Delete 5=Display 6=Release 7=Messages
8=Attributes 9=Work with printing status
Device or Total Cur
Opt File User Queue User Data Sts Pages Page Copy
QPJOBLOG DTKDEVKK01 QEZJOBLOG DTKC1 RDY 3 1
In there, it should list the user profile that ended the job
CPC1125 Completion 50 02/18/11 10:45:36.602141 QWTCCCNJ QSYS 0BF3 *EXT
Message . . . . : Job 892998/DTKDEVKK01/DTKC1 was ended by user DTKDEVKK01.
Cause . . . . . : User DTKDEVKK01 issued an immediate end job request for
job 892998/DTKDEVKK01/DTKC1. </pre>