When Jacob was on his way to meet his brother Eisav he became very scared of what could happen to him. How could Jacob, the patriarch, fear when he knew he had not sinned?
Jacob was scared because G-d had been so good to him that he thought that his merits might of been diminished. When G-d shows His kindness to a person, it brings that person closer to G-d making him/her realize how little he/she is compared to H”S. That feeling makes us see ourselves little in G-d’s eyes and very blessed for His kindness towards us.
A Tzadik ( perfectly pious person) is never static- he constantly grows spiritually from one level to the next, after reaching a higher level his previous actions are actually spiritually deficient compared to his current standing. Jacob was worried that perhaps due to such deficiencies he was not worthy of being saved.
