Whats goin on with him?

so i recently started potty training my son. he is doing remarkably well and is telling me when he needs to go and he goes as soon as i put him on the potty (like within 30 seconds....he doesnt take his time). i am really proud of him cuz he hasnt had one accident since we started. i only have one slight concern....he goes pee and when he finishes i praise him then he needs to go like five minutes after that then ten minutes after that. i noticed that when he goes he goes very very little so i am suspecting that he simply isnt finishing and thats why he needs to go again so soon. i always wait till he is all the way finished before praise so i wont startle him and stop the flow so idk why he is doing this. anyone have any opinions or advice to get him to go all at once, because its beginning to become a waste of water too