Multiple entries, 90days, entry before Nov 7 2014

Hey, i got a Multiple Entries M type 90 days. I am currently in china since 11th of May, some where around 1st week of august i will go to HK and back to mainland on the same day.

Will it be any trouble if i just went there for a few hours and return to mainland? Just worry they will be curious and ask me a lot of question and things. I am doing some jewelry purchasing and material sourcing in GZ and ShenZhen
Thanks