I'm not sure if its bad or neutral, I always cover mine so I don't get the algae, I think in general, algae is not good for your plants. Algae eats nitrogen and is potentially taking that away from your root systems. I know if algae covers your roots, they will just suffocate the roots, killing them.
I imagine its is like having a tape worm. You probably wont die, but you still have a parasite eating nutrients your body was going to absorb. So I'm 99% sure your plants will not even notice the algae.
Anyway yeah, you can buy fancy cover for your cubes, or just cover them with tape. If you cover them now, it will make the algae slow/stop growing. But the algae should go away once you bury them in coco anyway