BRMS tells you what tapes to mount. It's not going to tell you to mount a
tape if the tape has unexpired files on it. For example, if I use BRMS to
back up my daily data and put 14 days retention on it, and my quarterly
data and put 400 days retention on it, BRMS won't tell me to call Iron
Mountain and ask for those tapes until those days are past.
I suppose you could have done something outside of BRMS, like stored a
file on there with permanent retention.