Apparently this was their AM feed and most people listen to their FM feed. And they'd been doing maintenance lately where they'd be down for days at a time, so may not have seemed unusual.
Plus they're a really small station and their listener base skews old and people are kinda apathetic.
The bigger problem I guess is that they themselves appear not to have been doing anything to monitor the signal as required by the FCC. But I really doubt they get audited much or ever.