Tape drive is doing one extra unload

My 3581 L28 LTO2 tape unit is doing an extra unload and I can't figure out why. 
 It has not always done this.  Here's the sequence of events:

1.  Tape device is in vary on status.
2.  SAVLIB ENDOPT(*LEAVE) is performed on tape in slot 1.
3.  Device is varied off by a command running from the job scheduler.
4.  The HMC moves the tape IOA and IOP to LPAR2.

5.  Tape device LPAR2 is varied on. 
6.  SAVLIB ENDOPT (*UNLOAD) is performed on tape in slot 1 and all the 
libraries fit on tape1.
7.  Tape device on LPAR2 is varied off.
8.  The HMC moves the tape IOA and IOP to LPAR1.
9   The tape device on LPAR 1 is varied on.

All these events take place between midnight and 0630.  When I arrive in the 
morning, the tape is sitting in slot 3, not slot 2.  Step 6` should unload tape 
from slot 1 and load tape from slot 2. 

Any suggestions?

Thanks,

Bryan Burns
M.I.S. Department
ECHO, Incorporated