I hadn't heard anything about a potential deal in the works, and the mainstream media in the western world was completely blindsided by the deal. But this has become Israel's pattern in recent decades. The Oslo Accords, Israel's peace deal with Jordan and other agreements were negotiated under a cloak of total secrecy because officials didn't want public sentiment to potentially destroy negotiations. And there could potentially be other "peace deals" in the works right now that we don't know anything about.
President Trump is touting this as a major diplomatic victory, and he is hoping that it will sway some votes in November. At this juncture, Trump is trailing badly in most polls and he needs another miracle like we witnessed in 2016.
But it was really Israeli Prime Minister Benjamin Netanyahu that was the driving force behind this deal. He has been seeking to build relations with the UAE for many, many years, and this deal is the culmination of those efforts.