yeah that's definitely the connectors, mine were bad for a while after I got my M3 simply but eventually you wear the points down a teensy bit past all the nasty oxides and down to the good conductive metal, just never blow on it to make it work, that adds moisture and gets things corroding and bad contact-ee again
if it really bugs you you can clean them with Alcohol (no oxides from residual moisture) and something very mildly abrasive, course if the grubby points are in your M3's SD slot or inside the DS itself then you can just sit there for a while inserting-uninserting-inserting-uninserting-etc for a while stop when you get bored/aroused but yea the problem will eventually go away, mine did... took a while but it never does it anymore
and I don't think you can make a firmware patch for dirty contacts... lol YET... give it time