In DS9: The Ship Worf is really mean to O'Brien while Muniz is dying. He practically taunts the Chief about Muniz's impending death. Worf may be a "Klingon Warrior" but he's never acted like this. Not when Tasha died or when any other crew member of the week passed away. Worf grew up with humans; he was raised by humans. Why would he choose to be mean to a friend that he's known since his first assignment on the Enterprise while that friend is grieving? Especially since Worf didn't act like this when isn't a normal behavior for him. I've read pretty much everything on Memory Alpha for this episode and there's no explanation that I can see.
Worf tries to make up for it at the end when he sits with O'Brien in front of Muniz's casket. But that doesn't explain his behavior during the rest of the episode.