I didn't touch any grave during my first run (except Jake's of course).
**spoilers**
In my second run, I read more thoroughly Thelyron's diary about his motive for fiddling with Star Stones. So I figured, if the guy's wife is dead and he wants to revive her, she probably ISN'T in her grave. I wanted to make sure this time, so I dug it up. BOOM. Way to reward critical thinking.
Critical thinking: Keep the rest of the party away from possible traps.