The IRS wants to know who purchased. Last summer they made an announcement about every transaction needing to be listed was forthcoming but people rallied. Nobody wants to list every cup of coffee! Bitcoin and digital wallets are changing things and the IRS is just trying to catch up.
I could argue that you didn't sell for a reportable gain and no need to file. I could also argue that you sold and should file. A trade is considered a sale so you did essentially sell for the goods.
The IRS is concerned about taxing your profit. They are trying to figure it out. No need to worry.