Prayer answered or Coincidence ?

During the 1990s my late father needed an operation and as I had recently converted to catholicism I decided, without telling my parents, to have a mass said for him. His operation was due to take place in February of that year so I made the request to the church in early February, rather hoping that his mass would take place in the same month as the operation. The date allocated was in fact 26th March. My father was not a religious man and the thought of a mass being dedicated to him would have been distressing but I said in prayer - " I know my dad does not believe but please let me know that You are with him" The operation did not take place in February - it was rescheduled for - 26th March at 6p.m, - the very time he was having the operation! What seemed odd to me at the time was that far from declaring it a miracle, many devout Catholic friends said - What a coincidence!