Day 20 of flowering. Some pistils turning brown?

Strain is bubba kush currently in day 20 of flowering. Two bud sites are turning brown already. Looked at a bunch of fan leaves under 30x magnification front and back. There is no sign of any bugs. Bud sites in question are in the middle of the plant so no temp issues there. Looked the plants over pretty good and no signs of a hermie either so I don't think it is pollination. Anyway here's a couple pics of the two bud sites. Any ideas would be appreciated.

I think I can help but can u give me some more I fo esp nutes and medium....thanks

Thanks for the reply. I have six plants all together. All are in soil. Using Fox farms full line of nutes. Last dose was big bloom, grow big, tiger bloom, and beastie bloom. Also all other plants are fine.

is it possible that you dripped some nute feed on the bud, this is a slight chemical nute burn from either splash...or pushing the feeding a bitt too hard on the two that arnt quite up to it, u certainly have ur nutes dialled to the max,

Alright going to back the nutes back a tad. Hopefully that helps. Going to keep an eye on that one. I'll post if it progresses.