The exclamation mark has been there, possibly since the first version released. It signifies that Notified "captured" some kind of popup notification, and is a placeholder until they get the full set finished and released.
Seriously, I'm pretty sure it was in there since the first version. I believe turning off the Badge setting in Notified's settings will both disable this as well as the badge on the actual Notified app icon.
Seriously, I'm pretty sure it was in there since the first version. I believe turning off the Badge setting in Notified's settings will both disable this as well as the badge on the actual Notified app icon.