I had a similar experience back in 1995. I was trying to make Fe-containing nanoparticles using a microwave plasma from ferrocene dissolved in toluene, and quite by accident, the carbon was transformed into C60 (but not nanorods). Back then I didn't know what C60 was. I am not surprised at that synthesis result.

The fact that nanorods adsorb water at low humidity is not at all surprising. What is stunning is that they release the water at high humidity!