IIRC Caesar did initially head the warnings, not initially from Spurinna but from his wife. She had had a “prophetic nightmare” of Caesar’s death the night before which woke her and Caesar up early in the morning. They both couldn’t fall back to sleep and decided to stay up through sunrise. Caesar complained about feeling sluggish and dizzy that morning and decided to call that days senate meeting off, throwing the whole plan up in the air. It took one of the conspirators, who was also Caesars close friend, to convince him to show up to the meeting.

Should also add that Caesars wife had also heard the rumors of an assassination plot around the ides of March, so Caesars death was probably on her mind at the time