Whenever I do pull-ups or chin-ups, I start getting these little calluses on my

[Supernova1337]

palms...? In the area of my palm where the loose skin get's caught between the bar and my fingers. Am I gripping the bar wrong or will they stop appearing once I get used to it?

Here's a pic for reference to the spots I'm talking about(not really my hand):

http://i294.photobucket.com/albums/mm101/supernova1337/Hand.jpg

The problem is worse for pull-ups than it is for chin-ups...