No, they don’t do that, they would rather spend money elsewhere. Imagine the time sending emails for a false positive that even effected a single percent of their user base of many millions of people…it would take longer than it is worth.

No one posted what the specific detection was, but it was probably a Generic signature, they use those so one signature can catch many forms of malware.

Avast! is very low on FPs…I mean very low…so while it might be a bit much to think this is a “hopefully once in a lifetime event” (if you mean a FP in general), take heart that you have what is at any given day the AV with the lowest false positive rate possible.