It looks like a young calyx and not a male flower, which generally grows on a little stem.
I am sure your plant is not trying to pull a swifty on you, just a late bloomer.
Feminised seeds however are not 100% guaranteed to be female, a very rare male may appear, but most often if feminization hasn't worked properly with a seed, a hermaphrodite plant results. At this stage there is no need to panic and certainly no need to chop it down.
Hope this helps, Organoman.