Yes, it's lens flare, however the monochromatic nature of laser light also probably made that possible.
You can minimize it as much as possible, but any/all optical elements have SOME chromatic aberration, the same thing that makes a prism spread white light out into a spectrum. Each frequency has it's own index of refraction through a certain medium.
When taking photographs with a full spectrum source such as incandescent or sunlight, or even a multi-line source like a Xenon flash or flourescent light, the number of frequencies spread out means that even if a particular color is just right, there's so little of that one precise line, you never see the lens flare being "just so".
So even though there probably is 532nm light in sunlight or flash sources of light, the aperture is going to be way different anyway when taking those pictures.
With all that pure 532nm light, and it being the only you just hit a sweet spot in the refraction of the lenses where it all bounced in that neat circular interference pattern... (you can see some constructive/destructive waves in the circles as they progress inward too... neat!)
So it was a "perfect storm" of exposure, aperture, and a single line coherent light source providing all the illumination for the shot that caused it.
LOL
