Hi skyystorm -- I haven't the same model camera as yours so I don't know how much access you have to the mirror, but with my experience with telescope mirrors and lens systems I can only say that the safest way to try and rid the mirror of dust particles is by very very gently brushing it off with an optics lens brush, mirrors have very delicate coatings and you can't use lens cleaner on them, nor cleaning cloths or tissues without risk of scratching -- use the brush type commonly found with the airbulbs. Pressurized air can sometimes work for the finest dust (but it can sometimes also make things worse), and if humidity hasn't made any of it stick to the mirror. If you can't find an optics brush then a new clean, very soft camels hair art brush (the type for watercolors) will also work. If you can't reach the mirror to use a brush this way then I'd say take it to a camera repair place for the maintenance.
One other point --- keep your camera dry and away from humidity and heat -- these are real enemies of your optics.
Good luck!