I like mysteries.
Whenever science can't explain something that we observe, then clearly, either the observation is wrong, or the science is wrong.
From this temporary paradox, eventually will come better science.
Don't jump to anomalous conclusions, try lateral thinking, such as Roberts and Nimmo suggest - e.g. an evolving orbit.
You probably *can* safely say that Enceladus has not been in its current near-stable orbit for over 30 million years. But let's see how the story develops, eh?