I suspect that the values returned in my NTP peer offset monitor are being pushed into an absolute value rather than remaining signed, thereby not showing me whether or not the server is gaining or losing time.
1) is this true as the default? 2) if 1 is true, can I do something about it?
I guess you're right. The NTP plugin only displays the jitter, not showing if the offset is a positive or negative value. If you need to know the offset, you're free to write your own plugin which can be a simple script running ntpdate and which output value ist the offset. Are you familiar with plugin development ?