[linux-lvm] lvextend doesn't extend the first time ...

[Kevin Buyting <rotaticus web de>]

gentoo 1.4
vanilla-sources 2.4.22
lvm-user 1.0.7-r1

I am trying to extend my /dev/vg/lv01 (EXT3) by 3Gig's so i did a 

# lvextend -L +3G /dev/vg/lv01

then

# e2fsadm -L +3G /dev/vg/lv01 

*making chkfs reporting errors ... fixing them*
... and nothing happens ... then i did

# sync
# mount /dev/vg/lv01 /mnt/somewhere
# df 

says it's still 80G NOT 83G! so i try again *fearing the worst*

# e2fsadm -L +3G /dev/vg/lv01

*making chkfs ... resizing*
again and get 6G more to my /dev/vg/lv01
files are ok... *the best that could happen* 8))

the question is:
how come it isn't extendet by 3G instead of 6G ?
what am i doing wrong?
just to know for the next time ...

thanks in advance for any advice