Having participated in the bring up and readying for market of several niche Android devices, I feel it would have been a miracle if they had hit their original projection. There are always last hurdles that you'll never anticipate up front.
I'm actually glad they are giving themselves some wiggle room. I want them to ship the device when it is ready, not to meet some arbitrary point on the calendar.
When I placed my pre-order a couple months ago, I had already anticipated it would ship in August or September.