SagePay token method plugin does not handle expired credit card correctly. Namely:
when transactions are returned with status 'INVALID' and SagePay error '5013 : The card has expired' when PBA-S reports the transaction as 'ERROR' status and triggers the '513 Transaction finished with error' event.
The problem will be fixed in future PBA-S update that will be released after 4.5. Bug is PBAS-26643.