generic agent tests for some criteria (state new and older than x), then sets a priority or a state change (I'd go with state change), which is acted upon via Notification (event).
Within Generic Agent "Change Time" might be relevant. You have a "before" and "Last" entry. they count for time that has passed. It's awful english, but if I recall correctly,
"before" means before the set time [ago] and "last" means after the set time delta [ago]
Or, in other words, filter for "new" and "change time" before (greater than) (max time), then set new state "level2" then notification (event) on state change, alert level 2, 3 etc.