The things were mortars, not rockets. Mortars are actually much more accurate and can be aimed. And the shells fell on the Palestinian (Gazan) side or the line. If fired in succession, they could be walked into the border if, that was the intent. Somebody was apparently doing target practice, probably as a warning that they can hit stuff inside Gaza, if a target presents itself. Hamas is not beyond playing Israeli head games. The IDF will send in a patrol next week and be shocked, shocked, if it is fired on inside Gaza.
from the article: Mortar shells fired at Israel land in Gaza, injure 6 Palestinians