White Widow Auto - First Real Grow

My seeds have germinated and I was just about to plant them in their pots when I noticed something that resembles mildew on the walls of my tent. Is this mildew, mold, or anything that needs to be addressed? It's the white powdery stuff in the pictures. It's in different spots all over the tent walls. When I wipe it off it comes off easily and there doesn't appear to be anything on my fingers and it doesn't have any kind of a smell. I took apart the humidifier I've been running non-stop for two weeks and it definitely has a mildew smell coming from it so I'll be getting a new humidifier. Before I get things planted and off and rolling, should I sanitize my tent? I set it up brand new about two weeks ago. I was running the tent with the light, exhaust fan, floor fan, and humidifier to see what temps and humidity would be like. Before I put pots with soil in the tent the highest the humidity got up to was around 60% with a temp of around 68. After putting pots in the tent the humidity got up to 75% and the temp again got as low as 68 degrees. If there's any other info that might be helpful just let me know. I want to get started the right way. Edit: I went in and wiped it all down and it appears to have been dust, but at least it helped me discover that my carbon filter was a little too close to the wall, so at least I prevented a potential problem. There was a little pocket of the fluffy stuff where the filter was almost touching the wall. It would still give me some peace of mind if someone could confirm that it looks like dust to them too 😅 Edit 2: I'm just going to keep this as my first week and update as things need updating. First seedling popped through the soil on 8/19. I figured I'd also give a little info about myself if anyone is interested. I did one grow about 15 years ago in a closet. As a newb in prohibition land and no one to mentor me, I bought Foxfarms TOP SOIL (you know, for the garden, not for pots) and a 250w HPS and did the best I could do with that. Two plants ended up yielding something like 30 grams so I gave up on growing until it was something I could do legally. I currently go through about 2 ounces per month of flower so eventually I'd like to be able to provide for all of my needs with my 4x4 tent. Even though I've got the "proper equipment" this time around, I'm still going to be extremely happy to get even an ounce per plant. Patience was a major ingredient missing from my first grow that I'm going to use a lot of in this grow ;) Edit 3: As of 8/21 all seedlings have broken through the surface of the soil. Will update with pictures in a few days. Edit 4 8/25: Seedlings seem to be doing fine. Plant 1 made it through the soil about 36 hours ahead of plant 2 and 48 hours ahead of plants 3 and 4. For simplicity, after this week I'm just going to say they're all on the same day. I'll count 8/21 as day 1 going forward. I changed the light to 20 hours on 4 hours off to help keep temps up. Watered them each today with 1/4 gallon of water ph adjusted to 6.5. I'll wait at least another 3 days to water again. Looks like the leaves might have a few little trichs on them already.