When he goes to the mound and says something to a pitcher, he's speaking from experience. He's telling the pitcher what he's supposed to feel like, because he's been out there in key situations. He has the ability to get that across.
Just the fact that he was able to throw from the mound probably tells us it's not anything serious.
It's not an easy decision, obviously. But Heredia shouldn't be on the mound for me if I don't have confidence to do something like that. It's not an easy decision to make, but it was one I felt I had to and then just live with the results.