Unless your machine has a low bobbin warning.
I have found that my bobbin rattles a little when very low of thread, I have metal bobbins. I suggest if you have done a lot of sewing on that bobbin that you watch your sewing a little more closely. I usually catch my empty bobbin fairly quick, now. I have sewn probably a good 20 feet worth of chain piecing with no bobbin once, it was a different machine and it was 3am.