The "This never happened to the other fellow" line was all Richard Maibaum.  He admitted as much in an interview (Starlog #68) and even gave the back-story to it:

"We had this plastic surgeon idea.  Bond had to have plastic surgery because he was being recognized by all his country's enemies.  But we thought that was awful and threw it out.  Finally, I came up with that line, when the girl leaves him flat after he rescues her."

When the interviewer pointed out to him that the audience laughed at the line, he responded:

"Because it is funny. The audience liked it.  It said, 'Look, you know it's not the same James Bond, so we're not going to kid you or do anything to excuse it.  You'll just have to accept that this just isn't the same fellow."