EDIT: I was thinking more about what I posted so I checked out the Nicehash website as it did seem hard to believe they had such a high withdrawal amount, and the first thing I seen was "Payments from 0.001 Bitcoin". So something doesn't add up with the OPs story.
I've been using Nicehash for many months now and it has been my experience that they do not pay out less than 0.01 BTC.
I don't use them so I was only going by what their Seller section shows on payments. If that is the case I would definitely open up a ticket with their support department. Seems bitcoins price goes up all of these shady pools and exchanges get even more greedy. Once you get your money off of them I would avoid using Nicehash in the future, as there are a lot more trustworthy pools to mine at and which don't gouge you with 3-4% fees.