I think you should not let your GPA haunt you. Regardless of what your GPA was, it is what you learned in school that is important. Your degree was what you needed to get your foot in the door in industry. Now is your chance to accept your new challenge at work, put the past behind you.
Also, everyone has their strengths and weaknesses. Sometimes you may understand something very quickly and other times it may take a few tries. But what is important is to not be afraid to ask questions. Also, learn who would be the best person to help answer your questions.