I doubt they did this, but I was just thinking about this problem-- Maybe they could have analyzed the plaintext password and stored information about the type

I doubt they did this, but I was just thinking about this problem-- Maybe they could have analyzed the plaintext password and stored information about the types of characters it contained and number of characters. Then they salt+hash the plaintext password and store the resulting hash. Now they know a little about the characters and length of the password without knowing the password itself. Again, I doubt they did this.