Hi, I am no expert but may be able to offer assistance.

Firstly the questions: Does it happen to all the songs? Have you tried it with other files that extra data would be more evident?

Now my thesis: If it doesn't happen to all the songs then it is probably just something that sometime happens during the recording/encoding process. I run into that a lot. You should try testing it with another kind of file to be absolutely sure.

If it does happen every time, you are probably correct and I have no idea of what the solution would be.