Not trying to sound like a wise-***, but when was the last time you had your torque wrench certified? When you put it away, do you back it off to 0, first? If I'm not mistaken, the most common cause for rocker arm failure, is over torquing during installation. As everyone else said, I'm sure 3 lb/ft of torque isn't going to make or break your installation, as long as you KNOW your particular wrench isn't giving you stupid bad readings. It won't hurt anything to have it certified once or twice each year, depending on how often you use it, especially near 0, or close to its maximum rating. You might be surprised at how it checks out.
Although I haven't made a living at it for years, I was trained (trade school) as a machinist. One thing instructors constantly hammered into our heads, was to make damn sure your micrometers, verniers, depth gauges, bore gauges, etc., were REGULARLY checked against a known, accurate standard. I don't see torque wrenches any differently.