I restored a backup file (it's used as a template for new databases) as a new database. Normally as part of this process, I take a full backup after the restore, but this time I was called away on another issue before I could do that and in the meantime, my regularly scheduled differential backup job ran. It successfully took a differential backup of this database without throwing any errors. Conversely, the log backup job failed correctly reporting there was no full backup available.
I have read in multiple places that you cannot take either a differential or a log backup without a full, so why is this particular database allowing a diff? Has anyone else ever encountered this behavior?