Short answer: no. I've never been concerned entering a bathroom unless in a very dark location, very remote location, or bad neighborhood. Pretty sure I've never asked a guy to walk me to a restroom in my life.
Also, most restrooms in large casinos are in high traffic areas, well lit, and camera monitored. Vegas casinos are hyper aware of risks to intoxicated gamblers. I tend to only go to the "upscale" casinos which seem to have restrooms pretty well located now that I think of it. Moral to the story - be aware of your surroundings - and only go to fancy casinos