It's never bothered me, but I did hear Dick Gaughan do a rhyming first verse in my favorite rendition of the song. As I read it, it goes like this:

Oh, the summertime is coming (he sings "has come")
And the trees are sweetly blooming,
And the wild mountain thyme
All the bowers are perfuming.

Then Emmylou Harris and the McGarrigle sisters chime in, and I pretty much bliss out and lose track of the words. ;)

M