On the other hand, you may have some borrowed time. I've had tanks leak at the top seam before, and lower down it was fine. It sounds as if this could be the case since the puddle has dried up.
Yes and no.
For multiple years I had heaters in the tanks and kept the tanks a constant temperature. The light was controlled as well.
A couple years ago I removed the heaters and lights come on randomly.
Both yielded the same result of the neos taking time off during the winter.