Why did the Iron Dome not intercept the rocket from Gaza Monday morning?

Trails of smoke from the Iron Dome defense system after a rocket was intercepted over the Golan Heights, January 20th, 2019 (photo credit: IDF SPOKESPERSON'S UNIT)
Trails of smoke from the Iron Dome defense system after a rocket was intercepted over the Golan Heights, January 20th, 2019
(photo credit: IDF SPOKESPERSON'S UNIT)
On Monday morning, a rocket from Gaza struck a private home in central Israel, wounding at least seven people.
Why did Israel's Iron Dome not intercept the rocket?
Investigators at the scene told the Hebrew daily Maariv that it is estimated that the rocket fired was a missile that can reach a range of more than 100 kilometers, carrying a 125-km warhead.
The rocket is named J-80 after the head of the military wing of Hamas, Ahmed Jabri, and according to Hamas – since it travels on a nonlinear path – it can not be intercepted by Iron Dome.

Hamas is reporting that the missile was launched inadvertently, as the terrorist organization claimed earlier this month when two rockets were fired toward Tel Aviv. The Hamas sources said they believe the rocket system might have been triggered due to lightning; there was rain Sunday night in Israel.
It is unclear if the firing was really a result of poor maintenance by Hamas or a retaliation to the events on Sunday evening at the Keziot prison, which left two Israeli prison guards stabbed and wounded by Hamas inmates.
Palestinian media is reporting that Hamas sees the move as "fatal timing," given the April 9 elections and the likelihood of a strong reaction by Israel to the rocket. Prime Minister Benjamin Netanyahu said Monday that Israel will respond "with force."

Hamas officials started evacuating from their headquarters in Gaza in preparation for an Israeli attack, according to Palestinian media.