Your servo is being told to go to pos 0 and then move step by step to pos 180
for(pos = 0; pos < 180; pos += 1)
{
myservo.write(pos);
delay(15);
}
this tells your servo to go to pos 180 and then move step by step to pos 0
for(pos = 180; pos>=1; pos-=1)
{
myservo.write(pos);
delay(15);
}
So what ever reading you get it just move back forth!
Mark