Due to the way that we fetch data via Airtable at regular intervals (maximum of every 15 mins), we will always serve non-expired links. If your Stacker application has been open for a long period of time, it will automatically refresh the attachment links when we fetch new data from Airtable. This is a change Airtable announced a while back, and we already responded to it, so you should be all set with regard to Stacker — even if your use of Airtable itself may require some changes, depending on the use case (hence the email they sent). Cheers!