Steve, I've had similar problems with YouTube claiming copyright
infringements.  The most recent one used background music "Mozart -
Trio for clarinet, viola and piano K.498 'Kegelstatt' in Eb - 3
Allegro".

Mozart wrote this arrangement over 300 years ago.  The three artists
playing the instruments released their performance of this Mozart
arrangement under "Creative Commons License" and I was allowed to use
the performance as long as I gave credit to them.  I did acknowledge
and credit them in the video.

YouTube claimed that starting at 4 minutes and 10 seconds into
the video, the music infringed on the rights of a different owner.
I informed YouTube that:

1) The music arrangement was written over 300 years ago;

2) the three musicians released this performance under "Creative
Commons License";

3) The entire performance is over eight minutes long; it starts at the
beginning and plays for the length of the entire video -- nothing new
starts at 4 min. 10 sec.

4) The performers are credited during the end of the video.

I stated they had a serious problem with their copyright infringement
review process.  I never received a reply from YouTube.

In other cases I just check the box stating that this is not for sale.

I don't think you have anything to worry about.

Joel Holden