Neutral feedback

I received a my second neutral feedback. First one was for pick up only & buyer did not make contact until 10 days after sale and then wanted me to post as well as sell the items for half sale price - cancelled sale. LESSON LEARNT! Today I was left neutral feedback by a buyer who came and picked up the item from me 8 days ago.....was happy at time of pick up..........(I alway have a return policy of 7 days in listing) - never contacted me to say there was a problem, just left neutral feedback with comment 'thx". I emailed to ask if there was a problem & to say I do have a return policy if there is a problem. No response. Is anyone else having these sort of problems I  go out of my way to make sure the  customer is happy.