Top of plant flower dried out and is dying

I am less than two weeks from harvesting and my best plant had to be chopped down.

Yesterday I thought the plant was in need of water because the leaves were pointing straight down, so I watered it. Today I found it to be even worse.

Taking a closer look I realized the top of the main flower was so dry that it was like I had already harvested and dried the bud...

I chopped the plant down and its the only one out of 9 to have this happen.

Any ideas of what it could be, for future reference?

Thanks,

Sometimes parts of the plant mature faster than others so you can harvest separate parts at different times. The plant just sounds like it was ready for harvest.