previous versions of the "less" command were able to read files compressed
with the gzip tool. In RedHat 6.1, less is no longer able to do this.
Also, after viewing a file with less, my xterm window now displays the text
with the video inverted. That is, instead of black text on white
background, it is now white text on black background.
Prior to 6.2, the less command in Red Hat Linux could never look into gzipped
files. You're probably confusing it with zless.
Red Hat Linux 6.2 introduces this feature though.