Oat flake beer

I just brewed a batch of beer made from malt extract and oat and buckwheat flakes.
In the secondary there was a small deposit but as i bottled, I was very careful not to shake my fermenter so the deposit would stay at the bottom. it's been bottle for a couple of days and i noticed there is a deposit in the bottles( kind of powder). Do you think it comes from the flakes or is it some bacteria or soap residue?

I tasted it green and it was pretty good. Should I worry bout the deposit?

The sediment at the bottom is just the yeast settling out after carbonating your beer. Totally normal, don't worry about it! There is undoubtedly a little bit of sediment from your fermenter as well if you didn't use a bottling bucket, but just the same don't worry about it.