Along with that, the steam store is currently doing one of two things; A: Displaying text in a different language B: Fails to load more games C: (As of now) Failing to load completely
I can only assume that since it is cached information that it wouldn't show up unless you've viewed your account details within the last couple of days/weeks. Still, once this is fixed changing your password wouldn't be a bad idea.
Theirs a thread right now, on Reddit which trending around this topic. You view it here: https://www.reddit.com/r/Games/comments/3y7maa/something_is_really_wrong_with_steam_be_careful/ Short link: https://redd.it/3y7maa DO NOT POST PERSONAL INFORMATION OF OTHER USERS! You should only send this to Valve as evidence of a breach. It is protected information for a reason!
Here's some good news http://www.gameinformer.com/b/news/...al&utm_source=twitter.com&utm_campaign=buffer
The fact that steam is so bad with getting to these issues is just sad. Took them an hour or two to deal with it.....