White Dust on Leaves: HELP!!!

I've been through this and other forums and it seems that whenever someone mentioned white spots, the discussion goes to either Spider Mites or White Powdery Mildew. I don't believe it is either of those based on the pics I have seen of each.
1. My white spots are like dust particles, not blotches. (WPM seems to usually come in blotches rather than 'dust'
2. My white spots can be wiped-off. (Spider mites eliminated?)

1. I have AK48 and Northern Lights plants in a tent (32"x32" with a 400W bulb.
2. I am approximately 4 weeks into Flower and beyond this oddity, they look pretty healthy.
3. I DID spray them, repeatedly, with Dyna-Gro Bloom mixed at 1tsp/gallon. I now have read that I should not be spraying them anymore since that can add to humidity and bud rot.

Is it possible that these white spots are indeed White Powdery Mildew even though they are specks rather than Blotches?
Is it possible that the nutrient left a residue?
Or, are these tiny dust spots 'normal'? (I may just be a plant hypochondriac because the last time I saw oddities, I discovered it was just the plant maturing/changing and they were quite healthy. But, better safe than sorry!)

I would love your advise. For the moment, I am going to go ahead and take them out, wash them down, and spray with Neem Oil (4tsp/gallon) in case it IS WPM.

I included a bunch of pics. As you can see, the white dust is a LOT easier to see under the grow lights and seems 'amplified'. There are other leaves with slight 'burn' spots, but this is not prevalent.

UPDATE: This is now looking more like typical White Powder Mildew...Damn! I did the Neem Oil treatment 2 days ago and it is still getting worse. I washed out the inside of my grow tent with a bleach solution. Then I cleaned any specks I could find on my leaves. Then, I sprayed with Neem. It is worse.

So, today, I took them all out and washed EVERY leaf. What a PAIN!!! Then, I sprayed with a solution of skim mild, water, and potassium bicarbonate (plus washing out the tent again).

This is my first grow and I was feeling pretty good about how things were going. But, now I see that I am just beginning to step into the trouble zone and I hope I don't lose the whole crop. I am only 2-3 weeks from harvest, I think.

I totally created this mess based on stupidity and after reading about WPM, I can see that I created the perfect environment. It was too humid. The temps at night were too low. I sprayed the plants many times and even did it at night a couple of times. My tent was too crowded. Oh, I have SO much to learn!

Air flow!

I'm with you! I realized my exhaust wasn't on high enough (I turned it up and added hepa filter to intake). I had a fan, but it was stationary. I replaced that one with 2 oscillating fans. One is blowing across the tops of the plants and another is low and blowing from under the foliage. I really hope that does it!

What was neem gonna do for pm?

Just curious what you heard

I have read on lots of forums that Neem is one of the PM 'cures'. Unfortunately, there is no one 'true' solution. However, good air movement and humidity control seems to be universal in terms of prevention. I wish I knew that 2 months ago!