Yes, this is normal, given how ImageMagick, the PHP image editor WP uses by default, resizes images. Actually, it first expands the image and then scales it back again, sticking to its own resizing quality settings, not the one of the source image.
So, if you have a low quality image (say, 93.8 kb at 1900x400px) and the settings stipulate a high quality, you will get a lower compression rate on the resulting image. This won't make blurry pictures sharp, of course, but it will lead to a file size that is relatively higher compared to pixel sizes.
If this bugs you, you can lower the compression grade using the functions made available in the
wp_image_editor class. Two filters provide shortcuts you can include in your
add_filter ('jpeg_quality', $quality); // for jpeg images
add_filter ('wp_editor_set_quality', $quality) // for other mime types
$quality is an integer with values between 0 and 100.