It just means that someone is refreshing the thread so it goes to the top again. If there's no activity for a day or two, it will fall off the first page and be seen by fewer people. They are "bumping" it back up again.
I'm too new to know who you're talking about but I might be gaining on him. I try not to bump more than about once a week though. Hopefully that's not being too puuuuuuuuuuush-y.