Over the past month or so, Paypal has been selecting quite a few of our transactions for review. These have always happened from time to time--usually once or twice per year--but lately it's been more like weekly. While a payment is under review, Paypal holds the funds; we don't receive them, and we also can't refund or cancel the payment. Usually, their reviews take around 1-3 days, but it varies a bit.
If your payment is selected by Paypal for review, you'll receive an e-mail about it directly from Paypal. We'll also update your order status to "pending" until the review is complete. Once the review is finished, your order will ship out within one business day.
Paypal does not provide any information about why or how transactions are selected for these reviews, and it seems pretty random as far as we can tell. If you're on a tight deadline, we recommend paying via credit card or Amazon Pay instead of Paypal just to be on the safe side.