You've done a nice job understanding the parameters involved and getting them in line. I'd say you're on the border as to whether you have any algae issues. A 2ppm drop could be from stuff blown into the pool or maybe from a little algae. My guess is your safe to just stay at maintenance level.

Watermom's suggestion to test your loss overnite is probably the best way to tell......I seem to lose about 1ppm overnite. I'd test again maybe a couple more nights and see if your loss is consistent. As long as your water stays clear and you don't test more than .5 for CC's, I see no reason to shock.