what formats are you using? If they are all traditional tunes and NOT copyrighted arrangments of traditional tunes, then if you created the scores yourself, you should be okay.
Or if you can find sheet music showing that the exact rendition as you have it is definatley public domain...you should be okay
I would stay away from downloaded gifs, pdfs, etc - as the creator of the gif would have a copyright on the gif itself; if you create scores from someone's midi, I would think that you would at least want to check with them for permission.
my two cents worth