If you include .lss files, I do not have access to the source code, and so am unable to de-compile it. Sometimes I want to know about any potential lss inclusion, so I know to go back and check that source manually. Sometimes I do not care.
The ignore pre-compiled code flag is just a way to deal with that case. Possible match means you have an %include in a scanned agent or script library, in the case where you allow pre-compiled code in the scan.