After you finish a song, you have to live with it. If something bugs you just a tiny bit now, will it make you cringe years from now, every time you hear the song?
I'm a songwriter with a long history, and when I listen to my earlier albums, I'm embarrassed at the songwriting flaws that I feel I could easily have avoided.
Of course, you can't afford to bring your creativity to a halt out of the fear that you'll create something that you might dislike later. What I recommend is listening just once with a self-conscious perspective. For example, pretend that your song has become a TV theme song, and it's heard again and again by millions of people.
In that imaginary context, is there one little flaw in your song that stands out, something that you'd like to fix? If there is, fix it now.