Account Type in ASTPP 3.0 auto changing from Prepaid to Postpaid (Posttoexternal = 0, changes to 1)

Running ASTPP 3.0 on Centos x64. Running with the WHMCS integration Module as well. We notice that every few days, the account type changes from prepaid to postpaid (in the database under accounts table : posttoexternal = 0 changes to posttoexternal =1) I have to manually go to the DB to change them back to 'posttoexternal=0'. It doesn't seem to keep.