File size inconsistencies

[Bossman2099]

There is a .rar file on my hard drive with a file size of 1.05 GB and when I had dropped it onto my DVD the file size somehow shrunk down to 958 MBs instead.

When I transferred the file on the DVD back onto my HD it remained at its new file size, 958 MBs.

I have no idea what's going on, and I was under the impression that file sizes only changes when you're burning images onto a DVD, not a typical file.

Has my file on the DVD been corrupted, will it function as it should have despite the mysterious 50 MBs+ loss in size?