No, blind spots do not "disappear" as such, you just stop noticing them.
Blink one eye rapidly, with the other eye open, and then switch eyes. If the light is decent, you will notice that there is a fine web that is briefly visible as your eye blinks; that would be the blood vessels in front of (yes, in front of) the retina. The brain stops paying attention to them very quickly, because they do not change as you look around. Blinking makes them visible for a moment.
The same thing goes for blind spots, whether temporary or not.
A blind spot is stationary with respect to the eye, and as the eye undergoes the natural "image refreshing" operation known as a saccadic movement, the blind spot does not change, so it is ignored in your view of the world, just like those fine blood vessels, or like the huge gap they teach you about when you take driving lessons (except that particular blind spot is blind because there's a huge bit of wiring there instead of "camera" surface).
Blinking and some eye movements can make blind spots visible.
For a similar demonstration, look up at the blue sky for a while, and you will start to see white dots moving around at impressive speed. Those are the white blood vessels moving through your eyes. Wikipedia has a neat article on it, although its title escapes me at the moment. It's probably linked from entoptic phenomena or a similar article.
In any case, after being hit in the eye with a laser, regardless of the duration and intensity, you should seek out a specialist immediately. This is because there are some eye injuries that are only detectable when they are fresh, and some that are treatable only while fresh. And we all hope you will remember goggles the next time... much cheaper than the eye doctor.
P.S.: I hope you made sure nobody else was in the fog with you?
I had a very noticeable blind spot for about a week, then it went away. It is still there, however, and I can see it if I actually try to focus on it 
