Your call, but I'll personally move them so that they are entirely inside the film frame. Black bars don't exist on some projector systems, so subs located there get chopped out.
But leave the image centered for sure, regardless of subs!
Also: overscan. With the subs that low, you're likely to have them chopped off on quite a few TV's. Leave a 3.5%-5% margin on the bottom. 5% for maximum compatibility. That's likely to end up looking like one line in/one line out of the frame.