I'm not sure when does it happen.It doesn't always occur,I think it has nothing to do with my operation.

I have tried the P2P trade,I found I can only make deal with somebody  who offered the same amount and the same price. Can I buy some assets from others who sell lower price than my offered  and higher amount than mine?
Another question,what does atom and unit mean when issuing a asset . Where does the colored btc go and colored BTCs can be uncolored and used again?

In addition,I sent PM to you,pls check it. Thanks.