Same issue here, 2015 EX-L With Navi. I took it to the dealership and they are replacing it under warranty. There is no fix, just has to be replaced.

 

Another update,
It appears that my trim wants to pop off again, the same piece on the passenger door called the 'sill trim'. I will be taking it back to the dealer this week to give them a hard time about the 'fix' and get it remedied on a longer term basis.

 

As a -hopefully- final update and to bring closure to my issue. I took the car in to the dealer yesterday, they said 'we will make this right'. After an hour or so they gave the car back to me and instructed me not to use the passenger side door for 24 hours or so. The reason being they used some industrial silicone product called HondaBond in order to fasten it to the door panel. This time it looks WAY better and I would be hard pressed to see any difference from the factory install and the fix. Well done AutoNation Honda 104!