Is this successful potty training?

We decided to go with the method where you take your toddler to the bathroom every 15 minutes for 3 days. It was tough but it worked on the third day! Today is day 5. He now goes every 30-46 min. He does tell me "pee pee" when he has to go and we make it to the bathroom every time. The problem is sometimes he has slightly wet his underwear before telling me he has to go pee. Shouldn't he tell me he has to pee when he gets the urge and not when he has slightly wet himself? It's not like it's running down his leg or anything. Just a wet patch and when I take him to the toilet he releases and goes pee in the bathroom. Is this successful training or should I start overand do the 15min method for 3 days again?