Good! I was expecting more damaged files but sometimes it only takes one.
You can determine if the file is bad and fix it. I'm assuming a new layerslider plugin come with the theme update you just installed today?
If you haven't done so already, unzip the new install you got today and store it on your PC. Then find the file the scanner suspects. It's possible you will not find the file, meaning it was added during the hack.
If this should be the case, find the file on the server and download it to a clearly marked folder for safe keeping and delete the bad file from the server.
If you do find the file in today's download, open it in notepad or any other text editor you choose to use. Find the file on the server and open it with your text editor and compare the two files. You will be looking for something added to the file on the server. If you find it make a copy of the bad file (for safe keeping) then delete the added code. Save the corrected file back to the server and test.
Let me know if you have any questions. I do this often and I may not have made the steps clear to you.