In an acoustic singer-songwriter type song is it possible that the rhythm of a vocal run or vocal melody rhythm needs to be adjusted to fit the rhythm of the guitar better? I wrote some songs a while ago and I opened them up in my DAW and I hear certain vocal runs that fall in "odd" places over the chord changes and while the notes sound nice against the chord changes, there are some 16th notes in the guitar strum that don't really support the 16th note vocal run from a rhythmic perspective and it sounds like it doesn't work. I guess the question to ask is also, is there a place that vocal runs sound better over the guitar rhythm part or does anything go really so long as the melody works with the chord harmony?
Because we get so caught up in the creative process of our compositions, sometimes we can 'over think' things and get too bogged down in the detail. I could hear no problem at all with your example. If the vocal line works on its own, as does the guitar accompaniment, and their combination does what you want harmonically, then it's all good!