Palindrome Odometer

While driving the mathematics team to a contest, the driver noticed that the bus odometer read 21 912 miles. Being a lover of mathematical curiosities, she noticed that this number was a palindrome, reading the same backward and forward. The team sponsor said, “I bet it will be a long time before that happens again!” However, just 105 minutes later, the bus driver reported that the mileage again was a palindrome! How fast was the bus traveling during those two hours?

(Source: Mathematics Teaching in the Middle School, Sep-Oct 1994)