When I joined Mastodon I was @jefftk@schelling.pt. A few days ago that server had an incident and I moved to mastodon.mit.edu, becoming @jefftk@mastodon.mit.edu. This got me thinking about a wart in the current Mastodon design: while you can normally move followers with you if you switch instances, this requires the cooperation of the instance you're leaving. In this case that instance couldn't cooperate because its domain name had expired, but I could also imagine someone having a falling out with their local admins and getting kicked off in a way that precluded transfer.