From the aspect of liability shut it down! Other factors being closest suitable etc. From a logical standpoint if you reduce throttle and the warning goes away, advance and it returns, there is little if no doubt it is a bleed leak, isolate bleed systems and observe. A bleed leak is going to do nothing more than tear up soft materials within the nacelle. Just how much do you want said engine available for landing (altitude,rwy length etc). We all know SOP does not cover the unstandard condition. The engine has a redundant fire detection system.