What you have to understand when it comes to traffic violations such as this and speeding is that 80 percent of the battle is won by just showing up. 99.9 percent of people just pay the tickets so that's how they make their money. With the .1 second difference it's very easy to argue. Also, how many tickets has you mom had? If it's under 3 in the past 2 years, try going to talk to the prosecutor before the court hearing and see if he will amend the ticket to "inattentive driving" for just 20 dollars (on average) more, this violation is not a county/state code but a city-only code. This means that your insurance will never know and even if they did, they couldn't do anything about it because they are required to use county/state codes for determining penalties. But bottom-line is show up and plead your case, be VERY VERY VERY respectful to the judge and you'll probably walk away scott free.
One a side note, here's a joke for you:
A man in Colorado received a letter in the mail with a picture of his car speeding along the interstate with a ticket for $130. Frustrated with the new system but keeping his sense of humor, he mailed the police another letter with a picture of $130 dollars in cash. Three days later, the man received another letter from the police department with a picture of handcuffs. The man then paid the ticket.
Nick