3rd Gen My M card is not connected?

I turned on my DS last night and started my Leaf Green Version. I pressed A at the start screen. Instead of finding the continue, new game and mystery gift options it said "Your(or The. I can't remember) M card is not connected." and automatically started a new game when I pressed A. I freaked(or is it froke?) out and turned off my DS and pulled the game out. I blew on it and put it into my GBA and it worked fine.

Why did this happen and what is a M card?

Only thing I've ever heard of like that is the 1M sub-circuit board. I have no idea what that is, though. It happens on FireRed ROMs all the time, but I'm not sure why your actual cartridge would do that. It's not even FireRed.

Its nothing to worry about, that always happened to me. I was like you when it first happened to me, but then I soft reset it and it went back to normal.
I don't really know what happened but I just did the same thing everytime it stuffs up again.

Nothing happened to it it just was dirty