I wasn't bothered by the coincidence, but rather by how easily the heroine assumed that these events--a distant relative's death from natural causes and the disappearance of a local person--just HAD to be connected. It felt a bit clumsy, a bit contrived. I know that history is full of crazy coincidences, but as a reader, I wasn't sure that it worked.
I felt a little manipulated by the author.
HOWEVER, my husband, a cognitive psychologist, had a different take. He said that the character's insistence that the events had to be linked exemplifies two things. First, that people naturally look for patterns, even when no patterns exist. Second, people feel the need to account for extraordinary events with extraordinary explanations, even when a common explanation would suffice (also called the "Spectacular Explanation Fallacy.")
So, for example, have you ever been humming a tune, and when you next turn on the radio, that same tune is playing? Or have you ever dreamed about a friend, and the next day she calls you? Strange, right?
But how do you explain it? A divine being at work? ESP? Fate? Alignment of the planets? Jung's collective unconscious? Producers manipulating your life? (okay, think Truman Show for the last one).
So I'm curious about two things: Have you ever been thrown off by a coincidence that seemed too jarring to be credible, as either a reader or as a viewer? Have you ever experienced a coincidence that's stranger than fiction? So, ultimately, should a coincidence be plausible?