My guess is that means their new strikes are coming out in May. That's the month they used to always put their new ones in play. Every so often they vary from that, though. Like the 2nd 2002 series they put in on an October to take advantage of the "patriotic" craze going on.
Also, since they typically order 1000 strikes at a time (it used to be almost every two months), and with the price they have to pay for strikes nowadays, they don't want to get stuck with 500 left-overs. Those, they would always just let customers buy from the cage. They never put older issues back in the machines.
But still...I can't imagine them leaving the machines "dark" for so long. Very untypical.