Yes, there is a second production run with according to Yamato, improved tighter knee and elbow swivel joints and a tighter backpack hinge. I just got mine today, but haven't had a chance to take it out of the box yet.
If it's not in stores in Japan and HK yet, it should be any day now.
Unfortunately, I don't think there is any way to tell just from looking at the box whether whether it is a 1st or 2nd run.
I personaly, didn't consider the slightly loose joints on my 1st versions a problem at all. It never affected the toys ability to hold a pose.
Graham