Is it? If your threat model includes Mossad (or really any nation state) then you shouldn't have trusted those devices in the first place. Even if you didn't have "tiny explosives" on your bingo card, certainly bugs (hardware or software) should've been on there.
Given that those pagers are commonly used by doctors and none of them have been reported to explode, I think we can guess that it was targeted to the batches delivered directly to Hezbollah.