No Wiley it was not normal, for much of the war - apparently a standing order came out only a few weeks prior to Phil's little adventure saying that pilots could use the seat-type 'chutes if they wanted to. Phil by that stage in his operational career was not known for taking any further risks than he needed to and so decided to use the parachute that in the end saved his life.
Exactly what brought the aeroplane down is unknown. Phil remembered, just before dropping the bombs, everything going very hot, very dry and very red - then tried to find the aircraft's controls but couldn't, realised he was falling and pulled the ripcord. He was then hidden in a barn by a French family for a few months and eventually the invasion passed him. he returned to the UK in September 1944, and to Australia shortly thereafter.
Quite a remarkable man.