Perhaps just an idiosyncrasy. Plumeria do strange things and when they are coming out of dormancy, each plant, and sometimes each tip, has its own cycle. Of my 75+ potted plants, the majority of mine still are not actively leafing out. I need more hot days and warm night for them to really get going. For the last month we have bounced around from lows in the upper 40's to upper 60's, and days from highs in the 60's to mid-80's. Plumeria do better with warmer conditions and more consistently in those warmer temperatures.
