Got a refund for a missing item and the case was closed, but item showed up today...Now what?

[phantomkeetykeety]

I bought a listing consisting of two items, but only one of the two items arrived in the package a week ago. I contacted the seller inquiring about the missing part, but recieved no response from them. Several days later(today) I got the message from ebay that the case is closed and I have recieved a full refund for that listing. But, the missing piece also arrived today in a separate box. Since I got everything, I don't feel right accepting the refund. At this point, should I just go with it since the case is closed? I wanted to cantact the seller but I can't seem to find the option to do so now. Granted this is over a listing that cost about $5 total, but I really don't want to be placed on the seller's no-sell list or something. I buy things from them occaisionally and would like to do so again. Note I haven't yet left feedback. Should I just leave positive feedback and call it a day? What is the right thing to do in this situation? I can't help feeling like I've stolen something.