Delected on facebook, then added again without a friend request?

ok so i checked a friends facebook page and it sed '' add as a friend'' when i knew they were already my friend, i dont know if i was blocked?. i couldn't have been delected becaz the next day i went on there profile to check and everything was normal, i was on there friends list and could see everything on there profile, so im a bit confused i couldn't have been delected because i didn't send or recieve a friend request, so im thinking i was blocked then unblocked, is that possible?