George -

Moving data around within the TSM server storage pools has no effect
upon retention policies.  A policy change (retention or versions
reduction could result in a lot of data expiring: your system change
log should reflect such.  Or it may simply be the result of an
historic glut of data coming due for expiration, per your ongoing
policies values.  You can always run EXPIre Inventory with Quiet=No
to see more of what's going on, and you can limit runtime with DUration.

   Richard Sims