Sometimes, it takes months for U.S. troops to talk publicly about their own heroism. Take the case of Cpl. Winder Perez, for example. The 22-year-old Marine sustained a life-threatening wound from a rocket-propelled grenade in Afghanistan on Jan. 12, but survived when the ordnance didn’t explode. His life still hung in the balance, though — the wounds were serious, and the possibility of the RPG exploding while embedded in him remained. That’s the story the military shared in a news release it produced last week. It credited an New Mexico National Guard helicopter crew with risking their lives to rush…