Hello!
It is a bit too early to draw any conclusions. Children take time to adjust to the new environment. Some children go through separation anxiety during the initial days of joining playschool and hence they might remain withdrawn in the classroom setting.
However, does he behave the same in the home setting? Does he mix with other children or remains aloof ? Does he face the similar difficulties with guests visiting your house or he mixes up with them?
Next Steps
You can be watchful for atleast a week more. If the difficulty persists you can consult with me online for the same.
Health Tips
You can request the playschool teacher to spend some time with him and build a good rapport so he feels secure in the new environment.