Yes, this happens regularly - as the diff and price changes.
On fork.lol you can see the waves
It happened but it has never happened at such scale, i.e. Bitcoin mining has never been that slow.
Maybe because Bitcoin cash price has rised so much in couple of days, profitability difference for miners has not been this large before?
And here
https://fork.lol/ one can see that the surge of bitcoin cash mining profitability is because of the recent rise in BCH prise lately, not because of drop in BCH mining difficulty. Anyway in about an hour this will be fixed.