If I'm understanding correctly, the previous BSA Officer saw a customer on an exception (I'm interpreting this as an alert or indicator of potential suspicious activity), and does not review it if he/she has already reviewed it within the past year?
I would absolutely advise against that, as a customer's behavior and activity can certainly change, and although the exception isn't always going to be a true positive, it should absolutely still be reviewed in a reasonably timely manner. Depending on what other things there are to review at your institution however, the approach may be taken that the other monitoring devices employed are able to more adequately detect potential suspicious activity.
Our practice is if it appears on an alert, exception, case, report, whatever monitoring device we have, we review it to ensure that we either have a false positive, or report the suspicious activity.
Life is like a bicycle. To keep your balance, you must keep moving.