BP Price List changed unexpectedly

My Customer wrote -

We have noticed that occasionally the BPs Price List in the Payment Terms tab changes from Price List A (Trade) to Price List H (Retail) without anyone actually doing this. When we examine the history it usually appears to have happened at the same time that a user has made another change or added a note. All users are adamant that they have not touched the Payment Terms field. We canu2019t find changes in the other direction (i.e. H to A).

As anyone seen this and know what causes it?

Help much apreciated

Martin