Lifting- Got yelled at- Was I wrong?

I was lifting at my local gym tonight, which is really more of a "health club" type thing that has a side room with a rack, bench, smith, and dumbells. I was squatting, 275, not huge like some of the guys that come in, but enough. So I had the weight on, and was on my second set, and some old guy wearing an employee shirt comes running over and yells at my to rack it and I did. I'm kind of a regular, I lift a few times a week either at school or here, but I hadn't seen this guy before. He chewed me out for a good five minutes about safety because I did not have a spotter. Granted, I didn't have the clamps on, but I had the rails in. How do you get spotted squatting? Anytime I have ever squatted or seen someone squat, with the exception of like world records, the only safety device was the rails. Was I wrong? How the hell is someone going to spot me? Like if I fall, the rails keep me from being crushed, what else is there to do?