No i have not, and yes that IS against the rules.
castle through check??

Can you point to a specific game? The rule is that the KING cannot start from check, end in check, or pass through an attacked square. That means there are only three squares to worry about. It doesn't matter about whether the rook is attacked, and it doesn't matter about any other squares on the back rank.

No I haven't seen it done thru check... Its not a legal move... Also once you have moved your king or rook you are not allowed to castle...
Oh, ok. It was a queenside castle and the king wouldn't have crossed the path of check, but the rook did. So then what Metastable said makes sense. Never knew that, I thought that if any square between the rook and the king was attacked it was an illegal castle.

In one of my first OTB rated games, the opponent "castled" through check. I did know that rule, but missed it in the stress of play. Couldn't believe it when I saw the illegal move on review. Luckily I won the game anyway.

Hi...I just resigned a game thinking my opponent had castled through check. I now see it is only the King that cannot castle through check.
http://www.chess.com/livechess/game?id=375241628
My bishop only covered the path of the rook. I thought the computer had made an error, my mistake.

Just got hit with it myself. So, still an issue. Sadly I was distracted by real life and blew the game way before this one so I was not too upset by it. :-)

Oh reading this and given my example, does this mean that my opponent was only prevented from castling to the other side as that was not the way I, at least up to now, understood how the rule worked.

Correct. The way your opponent castled (long) they did not castle through check. The Rook is allowed to move through an attacked square, the King is not,

https://www.chessvariants.com/d.chess/castlefaq.html
Yup looks Lomé this is allowed if the king is not going through a path that would put him in check,
Has anyone else been playing a game and saw an opponent castle through check? As far as I know this is against the rules.