NEW YORK (Reuters) - JPMorgan Chase & Co (JPM.N) Chief Executive Jamie Dimon has given investors plenty to worry about throughout the year but they have shrugged off his cautionary remarks and embraced his couched reassurances. It might be time to reconsider Dimon's cautionary side after Merrill Lynch & Co Inc (MER.N) unveiled a $5.5 billion credit implosion last week.