Hi, essence3d! Welcome to "GotMead?" !!
What you saw and tasted is some crystallized honey. Honey is essentially a "super saturated" solution of sugars in water, with some other minor ingredients. Some varietal honeys, including eucalyptus, tend to form minute crystals of sugar over time. That has to do mostly with those non-sugar (and non-water) components of the honey, some of which which can serve as trigger points for the growth of the sugar crystals.
Although there is a theoretical danger of spoilage organisms taking root in the watery remains surrounding those sugar crystals in honey that has crystallized, I've never had any problems using it in a mead. But, I don't tend to keep honey around very long so if I do have any that has crystallized, it hasn't been that way for more than a few weeks. If you are unsure of the age of your honey, if it has crystallized, you might want to play it safe and use honey from another source.