If 3 or more answers of user having < 10 rep is deleted, the question gets auto-protected. This is because majority of the time, the "answers" are me-too posts rather than just answers and was implementedwas implemented as part of a feature request.
Is a bug, being tracked at Meta.SO: “Migrated from” banner looks wrong“Migrated from” banner looks wrong
replaced http://meta.stackexchange.com/ with https://meta.stackexchange.com/