topr8 - 4:25 pm on Mar 23, 2011 (gmt 0)

i don't know about cPanel i'm afraid.

but doing the maths, hot linking can be an issue.

say an avatar is 50k, then 20 calls is a Meg
20,000 is a Gig.

although seems a lot of page calls to me to get to 13.4 gigs

maybe you want to see if traffic spiked one day for some reason.
do you have a stats package included with your hosting?