Of course we all hope for your sake that you do not have an impregnated plant or plants but in my last run I evidently had a very late hermi that I was unable to spot. I did see the same brown pistil coloration and out of the entire crop I only found one single seed.
 
The pollination occurred late enough that seeds, almost totally, were not produced but the process to create them had begun and it did effect the quality of the bud.
You may not find a single seed due to how late pollination may have occurred but that will not be proof it did not occur.
 
I hope it is not the same in your case as was mine.