My son had a flu booster and hib vaccine.. now has lump under skin on leg where one of the injections were.. is this common?

Vaccines: A lump under the skin is not unusual after a vaccination. The injection is given into the muscle tissue to get the right antibody response. Sometimes the vaccine leaks out into the fatty areas under the skin and a more intense local reaction occurs and the lump forms. The lumps can last weeks and gradually disappear. This is not an allergy or a complication of vaccines. If red/hot c the dr