There are various phases of tooth development. As per the picture and the age mentioned by you, your child is now in the ugly duckling stage which means that the gap between the upper front teeth now seen is normal and a good sign that the process is going on well.
Next Steps
If the child is concerned for his esthetics and if there is a history of gaping between the teeth in your family, there is no harm in getting a OPG(Full mouth Xray done) and keep re visiting the Dentist who may provide with some dentofacial orthopedic treatment if there is a problem which is very beneficial at this age.
Health Tips
Apart from the gap issue you might keep a check on other habits of your child to get a non interrupted tooth development.