You are probably right. Checked some Hilton and nearby Sheratons, using Google Streetview, in cities like Phoenix, Tucson, Pasadena and Los Angeles

Every time when the logo on top of the Hilton building was in red, the Sheraton name was also written in red. While its street level sign could be in blue.

Sheraton Passadena:
https://goo.gl/maps/5Z1rpzYS3R42

Hilton LAX is also carrying both styles:
https://goo.gl/maps/seGWJjnjoZM2