Egypt is definitely concerned about the military activities being carried out by Hamas and Hezbollah on its soil. This article describes two recent finds in the Sinai desert:
"An Egyptian official assessed that the 266 rockets, 51 mortar shells, 21 grenades and 43 mines uncovered in northern Sinai were meant to be smuggled to Hamas forces in the Gaza Strip.
Last Monday, Egypt discovered a large quantity of ammunition intended for Hamas use near Ismaeliya, Sinai."
Last month, the Egyptians accused Hezbollah of plotting to attack Egypt as well as supporting Hamas in Gaza. They have sinced arrested 25 individuals and are searching for another 24.
So why would Hezbollah attack Egypt? Two reasons: Egypt had the temerity to accuse Hamas of breaking the Egyptian-brokered truce and thus starting the war in Gaza late last year. And Egypt is a Sunni Arab country opposed to the expansion of Iranian power, of which Hezbollah is a key element.