Any reason NOT to get an older child's flu shot at a pharmacy?

Last year my son's [13] pediatrician's office told me not to take him to Rite-aid, and to bring him in their office for a flu shot when I asked if it was ok to take him to the pharmacy.It is a bit of a hassle to get an appointment and a bit of a drive to go to the doctor's office. I really want to run him down the street to Rite aid and get it done right away. Any reason it's better to do it at the doctor's office? via /r/Parenting https://ift.tt/2lHn3Ey