Why lsof shows the file as open and fstat doesn't ?

[Yuri]

I am looking at one file which is actually a unix socket: 
/tmp/dbus-iQmkLjgxD6.
"lsof | grep dbus-iQmkLjgxD6" shows that it's open by a particular 
process many times:
ibus-daem 48407       yuri    4u    unix 0xc966019c        0t0          
/tmp/dbus-iQmkLjgxD6
ibus-daem 48407       yuri    5u    unix 0xc9569000        0t0          
/tmp/dbus-iQmkLjgxD6
ibus-daem 48407       yuri    6u    unix 0xc955e9a8        0t0          
/tmp/dbus-iQmkLjgxD6
ibus-daem 48407       yuri    7u    unix 0xc8d25000        0t0          
/tmp/dbus-iQmkLjgxD6
ibus-daem 48407       yuri    8u    unix 0xc9596ce0        0t0          
/tmp/dbus-iQmkLjgxD6
ibus-daem 48407       yuri    9u    unix 0xc8f9b19c        0t0          
/tmp/dbus-iQmkLjgxD6
ibus-daem 48407       yuri   10u    unix 0xc916619c        0t0          
/tmp/dbus-iQmkLjgxD6
ibus-daem 48407       yuri   11u    unix 0xc9547338        0t0          
/tmp/dbus-iQmkLjgxD6
ibus-daem 48407       yuri   12u    unix 0xc9589670        0t0          
/tmp/dbus-iQmkLjgxD6

But when I run "fstat /tmp/dbus-iQmkLjgxD6" it doesn't return anything, 
like this file isn't open at all.

Why there is such discrepancy?

Yuri