Hello,
If you’re using Windows and flashing an image that has partitions Windows can read, it may be the same issue as Checksums do not match - #82 by zvin .
So the image was flashed correctly but Windows wrote some files to the drive before the validation finished, changing its checksum.
The drive will most probably work fine for its purpose.
Unrelated to this issue, you should update Etcher, 1.4.9 is quite old.