It looks like you did the update to 4.2 correctly but you need to remember that a disc update is caused by an outdated ios. For instance.... You can have your console updated to 4.2 using the guide (like you have done) but still have that game prompt you for an update. This is due to you not having the ios installed of which that game needs in order to run. That game uses the newest ios53 which can be found on this site searching through the NSMB threads. Once you have that ios53 wad file installed via wad manager, load the game using the disc channel and you wont be asked to update. Myself, I am running firmware 3.2 which is very outdated but I am able to play that very same game without the update needed due to the simple fact that I have ios53 installed. Just remember that a disc update will not update your firmware (unless your below 3.4). Instead it will update/install ios', channels, and so on.