Temperatures in the center of Greenland's ice sheet never rose above -10C all summer, so it's hard to see how it could have lost any ice. Ice accumulation is nearly two standard deviations above the 1981-2010 mean for the same period, and it is very, very early in the season for such gains.
Both of Greenland's largest glaciers (Jakobshavn and Peterman) are growing at record rates, about 1km/year.
Icepacks and glaciers calve into the sea. That's what they do. It's Nature's way of moving the ice and snow away from the center and back into the ocean. If they didn't, the snowpack/ice would extend to the Equator, which is impossible, or the snowpack would be 5 miles high, which is not the case.