bug#10442: maybe a bug for "tail"

[yukuan]

When I user "tail -f FILENAME" to follow a file, which is continually growing, 
the output sometimes stops. When I press ctrl-c to quit and right immediately 
follow the same file, output would continue. And I found the file is growing 
while the output stops.
(BTW, it's a log file with timestamp, so I am sure the file is growing. And 
while writing this mail, the file in another window stops, again.)
Maybe it is a bug, or not. Please explain this for me.
Thanks!