Help!! I find pee everywhere...

DS is 3 He will be 4 in May. We have really been working on potty training a lot. He had absolutely zero interest for a while but has been doing so much better lately! He wears only big boy underwear, he hasnt been having accidents in his pants or in bed at night. He is going potty in the toilet, he is even pooping in the toilet now after much convincing! So I thought everything was great! Then I started finding places he peed. Like in a dresser drawer, or in his bin of legos, In once of my sauce pans in the kitchen cubbord. Really random places. He still goes in the toilet too. Its odd to me because he cant tell me why he is doing it he just says that he has to go in the toilet. I am getting really frustrated. I asked if he does this sometimes because he feels like he wouldnt be able to make it to the potty (thinking maybe he was holding it) He said no. I ask him to try to potty about every hour to hour and a half. Im really not knowing how to get this behavior to stop or if this is something that other people have had issues with in the past... Any advice is definately welcome. Thanks in advance.