He's probably right- time will level things out a bit.
In the mean time, if it's bothering you (I know it would bug me), you can spot treat by turning off the filter and using a dental syringe filled with Excel- gently squirt it at whatever you want to die!
Algae, that is.
Wait a bit then turn the filter back on.
Worked well on my BBA (which came and went with the new tank set-up).
The tank looks wonderful! Wish I had discus...