In a roundabout way, you are saying that your CO2 level and/or fertilizer level(s) may have been too limited for your plant mass until you slowed plant growth with a lower light level. Algae should be suppressed, no matter what the light level, if you have sufficient plant mass and plants are healthy and growing well. However, as others mentioned, it becomes increasingly more important to ensure stability as light increases.
If you are happy where you are, then it is no longer an issue. If you ever do decide you want more light or a longer photoperiod, Iíd first try to figure out why you canít get CO2 where you want it. You should be able to reach a full 1-point pH drop, and beyond, with pressurized CO2. If you do achieve higher CO2 levels, be prepared to adjust other nutrients higher, as well.
I would add something to that.
Raise light levels slowly. It's a big difference to jump from 70 to 120 PAR all at once. It's a shock to the system and all manner of algae could break out. I always do it over weeks/months. Another method is to have a higher "burst" in the middle of the lighting period, then slowly expand that over time.
And take notes and pictures. I take far more pictures than I post here. It helps me go back and correlate with all my tracking.