Yes, this happens over and over again (see my earlier comment). And indeed, it can effect your status and lead to unjust penalties.
I check my calandre every now and than and open dates appear all the time, no matter how often I've blokked them. Airbnb seems to claim this is a 'glitch' but I honestly think it's part of their strategy (?!).
This is what I did to prevent unwanted bookings and having to diappoint people. I've changed the start of my profile text: 'Please note: at this moment we expect not to have any AVAILABILITY anymore in 2017. Please don't try to book dates even if they seem open, this is due to a flaw in the airbnb calendar system!'
In case you still have some openings you could sum them up: Please note: we can only have guests in the following periods 10-16sept, 20-24oct, 3-10dec. Please don't try to book other dates even if they seem open, this is due to a flaw in the airbnb calendar system!'
Maybe this helps... I have not received unwanted bookings since I've added this text.