It only applies to older users and probably wouldn't explain this case, but Facebook has silently imputed a "like" before, in cases where the user never explicitly liked the page. There used to be a section on your profile where you listed favorite music, books, and films, and at some point a few years ago, they phased that out and did some heuristic processing on what used to be a free-form text field, to convert its contents to the corresponding "likes". That was somewhat annoying, since I hadn't interpreted the act of listing something on my profile as equivalent to a subscription request for that thing's feed.