Why hasn't the BCG vaccine left a scar on my daughter's skin?

My daughter is five months old. She was given the BCG vaccine at birth. The doctor had then given me an option to administer the vaccine either on the upper arm or on her thigh. I chose to get the vaccine administered on her thigh. My concern is that the vaccine has not left a scar. Most people tell me that the vaccine should be given on the upper arm and not the thigh. Should my daughter take the vaccine again? When should she be given the vaccine again?