That would indeed be pollen dispersed by air and gravity from an intersex flower, not powdery mildew.
Don't freak out, although it is far from ideal. I'd wet some Qtips and get a sprayer on mist setting. Dab the pollen up with the qtip. Then mist, and remove. Know that when you touch them bananas you're gonna likely get some more pollen falling out of it. usually fresh pollen falls 9like you have here). This is mostly due to the moisture content in fresh cannabis pollen. Oh, and you should've been cut off ANY airflow in that tent whatsoever (canopy and exhaust) until you're done.
depending on your ventilation system, any pistils you see in the next few days go dark and shrivel are likely transporting pollen down and should be considered pollinated. chase pistils down into the flower to the bottom of the calyx to determine if pollination occurred prior to consuming via smoking dried flowers
note: you should make sure questions with a diary are attached accordingly to the diary, it matters in some cases for the responders