Cocos2d - Moving the Layer/view based on ball movement - cocos2d-iphone

Question

My game world space is a rectangle of 4 screen sizes (2 rows x 2 columns )
I am moving the camera based on the movement of a ball. The ball position is set according to the physics engine.
I notice that, sometimes the ball changes direction slightly as the camera is moving to follow the ball.
Initially I thought it was sort of an illusion based on the movement of the camera, but when I draw a path, the line is of crooked at times.
I used some of the code behind the CCFollow implementation code (not CCFollow itself, but the code behind it), for following the ball
(I had issues with CCfollow)
Below is my Tick() function:
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- (void)tick:(ccTime) dt {
bool ballMov = false;
CGPoint pos;
CCSprite *ballData;
dt = 1.0 / 60.0f;
world->Step(dt,8, 3 );
for(b2Body *b = world->GetBodyList(); b; b=b->GetNext()) {
if (b->GetUserData() != NULL) {
CCSprite *tempData = (CCSprite *)b->GetUserData();
if (tempData == ball){
ballData = tempData;
ballMov = true;
ballData.position = ccp(b->GetPosition().x * PTM_RATIO, b->GetPosition().y * PTM_RATIO);
}
}
}
//
// Move the layer so we can keep looking at the travelling ball
// Code is similar to CCFollow code with some adjustments
pos = ballPosition;
if(ballMov){
#define CLAMP(x,y,z) MIN(MAX(x,y),z)
pos = ccp(CLAMP(pos.x,leftBoundary,rightBoundary), CLAMP(pos.y,bottomBoundary,topBoundary));
#undef CLAMP
pos = ccpSub(pos, halfScreenSize );
pos.x = - pos.x ;
pos.y = - pos.y ;
//calculate delta move towards the new position
if(gunShot){
CGPoint moveVect;
CGPoint oldPos = [self position];
double dist = ccpDistance(pos, oldPos);
if (dist > 1){
moveVect = ccpMult(ccpSub(pos,oldPos),0.4); //0.05 is the smooth constant.
oldPos = ccpAdd(oldPos, moveVect);
pos = oldPos;
}
}
}
//move towards the ball
[self setPosition:(pos)];
lastPosition = pos;
ballPosition = CGPointMake([ball body]->GetPosition().x * PTM_RATIO, [ball body]->GetPosition().y * PTM_RATIO );
//if ball is out of gameworld space then reset
if (!CGRectContainsPoint ( outerBoundaryRect, ballPosition)){
ball.visible = false ;
[self recreateBody]; //Ball is out of Gameworld, recreate it at the default position
}
}