ID be worried about hermies not not at week 6 my man! Even if they did pop nanners they wouldn't have time to produce seeds! Just keep an eye on them and pluck any nanners with tweezers if ya want! Fem seeds have always been trouble for me. Not saying I don't use them but starting to get away from them. But yeah you aint got shit to worry about even if they did herm on ya there won't be any dammage if they do it now!
edit
assuming you are indica and roughly 8 week flowering time
it's the amount of dark hours that trigger flowering response in cannabis, not the amount of day hours, so long as they receive 12 plus hours of darkness they won't hermie in flower ime.
and 1/2 hour, that's it.??