My barrel cactus has what looks like small pieces of cotton between the needles. is this normal for this plant?

Could be mealybugs. They have a white, woolly coating that looks like cotton and they like to invade cactus. You'll find more about them here a href="http://www.guide-to-houseplants.com/mealybugs.html" rel="nofollow"http://www.guide-to-houseplants.com/meal…/a