Well technically there is no FP in the auto sandbox as it isn't saying that it is infected, or the file system shield (which hands off to the auto sandbox) would have alerted. Al that ii is saying is that it meets a set of criteria in which it is considered suspicious(no digital signature, location, etc. etc.).
Since it also offers the choice of running in the sandbox or declining the offer, run it normally and remember the choice for this program, if the user is happy, what is the problem ?
The problem being you have compounded the issue by having set the auto-sandbox to Ask (I have too) not Auto, so you don't know if it might have let it run or not.