you don't mention the type of plane.
it is possible that something happened at the airport to indicate a longer delay and prudence dictated a diversion.
IN the USA, airliners are dispatched with at least two people in concurrence about the amount of fuel on board. ONE is the dispatcher, the other is the captain.
THEY must agree before the plane leaves how much fuel is needed and is properly on board. AND if push comes to shove and the captain wants MORE fuel, the dispatcher will almost always concur.
YOU took off with enough fuel. But things do happen along the way. You obviously had enough fuel or you would have crashed, and not made it to another field to get more fuel.
IN the USA you must takeoff with enough fuel to get to your destination, delays you are made aware of prior to takeoff, go to an alternate airport and then fly for another 45 minutes. (assuming an alternate is needed due to wx).
I (as a pilot) have taken enough fuel, ended up in a holding pattern with an almost indefinite further clearance time due to wx. So, even with a good amount of fuel remaining, I elected to proceed to another airport for more fuel. AS SOON as I suggested this to ATC they let me out of the hold and put me number one into my original airport (no emergency).
IF you ever have questions again, you should ask the pilot as soon as you are getting off the plane...after you thank him for a safe flight.