Does the PACKET_MMAP clock go backwards?

packet_mmap_clock.rs

let mut cap = packet_capture::Capture::new("enp68s0").unwrap();
let mut previous_time = (0, 0);
loop {
    let packet = cap.next();
    let time = (packet.tp_sec, packet.tp_nsec);
    if time < previous_time {
        println!("{:?}: {:?} {:?}", chrono::Local::now(), time, previous_time);
    } else {
        previous_time = time;
    }
}