You got Lucky..It must have been something "Dry"..like a hair..or dust...
I had the same thing...blew off the lens..and whatever it was it "SPLATTERED over the surface of the LENS
Not having a Lens pen available...
I used Zeiss Lens cleaning solution...
Here is how I did it...
Take a new clean Q-tip..and spray the Zeiss Lens solution on the end.. (DO NOT USE THIS Q-TIP...IT WIL BE TOO WET!!!)
Take another new clean Q-tip, and dap the front of it on the WET Q-tip...
THis will transfer JUST enough solution to the new Q-tip to do the job...
Lightly and gently clean your lens (3-4 Swipes..then done...Rubbing dirt around on the lens WILL SCRATCH IT!!!)
Use another NEW DRY q-tip and again 2-3 swipes to dry up any solution/ smudge left in there from the first step.
Lastly..use a can of compressed air and LIGHTLY (NOT FULL PRESSURE) blow off the lens to remove any fibers the dry Q-tip left.
if you perform this very gingerly, and do not get anything soaking wet..it will work perfectly!!!
THough the Lenspen is a MUCH better tool for the job...If you don't have one available..my method will work in a pinch!
Lastly..an ounce of prevention is worth a POUND of cure....
Go to your local hardware store, and get a 1/2" rubber dowel cap...
Clean it out really good and use it as a cover for the appeture end of the laser.
39 cents ...beats risking damaging the lens cleaning it!
Larry