CapriUni - I suspect, at least with the original songs - you may have the same problem as I;

frequently with my poems - or with lyrics and a tune, others will read them and tell me that they don't scan properly - but when we get a chance to check them out verbally it is due to the phrasing and/or accentuation of various syllables that I automatically give the lyric (which of course I know if I wrote it) and a differeing phrasing that comes more naturally for the person reading it.

I know this has also happened to me when trying to match lyrics up with tunes for songs I do not know. When I finally hear someone who knows the song sing the verse - it seems obvious - but trying to do it "cold" I can't make sense of the way lyric and tunes fit. Sometimes the difference is very minor.