Not uncommon where I’m upgraded on the commute into the airport. Typically it just automatically changes my seat assignment and “new” e-boarding pass is available. I only use my phone for boarding pass domestically. I’ve had occasion when gate agent calls me during boarding time and I’ve already uploaded my new boarding pass.

It would be absurd to require someone physically be present in the gate area if they checked in electronically. That would have been very frustrating and upsetting if OP didn’t clear. Needs to write an Alaska listens experience.