FireLite 5012 - Tamper Problem

I have a 5012 that throws a sprinkler tamper approximately once every 3 days or so. It always occurs at 12:38 in the morning. Then it self clears. The tamper circuit is conventional and dedicated. The actual valve is chained and inside a locked commercial space. So I know its not actually getting touched. Anyone have any thoughts on why and how to fix it?