I got a DX 5mw, I've had it maybe two weeks, and I lately I've noticed that around the dot, there is a fairly large(around 4-5 inches in diameter, with the laser about a foot from a wall) circle of green speckles. I'm guessing its dust, as I have no noticed it before. Is there any possible way to clean this dust off without taking the head off the laser? Or is that the only option?