Here is what is happening. In the murrine (cane segments), the external yellow is slightly translucent, and is placed over a bright blue glass. Where the yellow glass is thin, the blue glass below is visible enough to combine with the yellow to appear green.

This would be more obvious in some lights, and less obvious in other lights. For instance, natural versus artificial (outdoor/indoor), or brightness (sunny versus cloudy, or candle versus sunlamp).

Be well. I miss you. Jamey