Is it valid according the FIDE chess rule? From FIDE Law of Chess, article 3.8, it is stated as:


Now, coming to My game vs killin_pieces on lichess.org :

After move 9, situation was something like this: b1 was threatened by my opponent's light square bishop:

 

Still I was able to give him a discovered check on move no. 10.



which clearly contradicts FIDE Law of chess article 3.8.2.a, stated as :


  Castling is prevented temporarily: 
  if the square on which the king stands, or the square which it must cross, or the square which it is to occupy, is attacked by one or more of the opponent's pieces


Can anyone please explain me how can this be possible ?
The king does not cross b1 (only the rook does). It also does not end up standing on b1 following the castling. Hence, the quoted rule is not violated.