When the mouse goes over a notification and the user moves the pointer in and out of the notification, the close timer resets making the notification take longer to disappear than expected. The timer should continue where it stopped.
No way! This is an important usability feature. You can move the cursor over the notification to pause the timer to get more time to read it. If the timer didn't reset when you do this, then if you accidentally moved it out again while the timer was close to completing, it would disappear almost immediately. The timeout visualization adjusts so you can see what's going on; I don't think there's anything weird or unexpected about this.