lol. Yep, I have similar readings: 48, 42, 72!!!???, and 34 for hd. I actually used my electronic thermometer at various points on my mobo attempting to determine where this 72 was coming from, but ultimately couldn't find any hot components. All my HS's were warm to the touch but not excessively hot.
I'd say don't worry about it unless your system gets unstable.