Should I be worried if my baby has yellowish skin?

Yes. Call doctor! Babies with yellow skin may be jaundiced, a potentially serious liver condition. Call your pediatrician immediately and set up an appointment for your baby to be evaluated today.
Yes. This indicates your baby has jaundice and needs to be treated immediately to protect his/her brain development. Call your pediatrician and if no contact possible, go to the emergency room.
Yes. This could be jaundice which should be evaluated by your pediatrician.
Yellow skin. Pediatrician can do workup for jaundice, most likely physiological and temporary if your child is healthy otherwise.
Yes. Yellowish skin in a baby is concerning unless a doctor has examined the baby and diagnosed the color as a normal amount of jaundice (called "physiologic jaundice"). The color is caused by increased levels of "bilirubin" in the body. Increased bilirubin occurs if the body cannot get rid of the normal amount of bilirubin produced by the body, and/or the body is producing too much bilirubin.
Yes. Yes - this yellowish color likely represents jaundice. Jaundice is caused by an elevation in the chemical bilirubin that is released from the breakdown of red blood cells. If high enough jaundice can cause serious damage to infants and is a serious issue. Children who look yellow should be examined by their doctor asap to determine if it is seriously elevated or not.