AITAH for not seeing a customer while doing the hourly sweep around the store

So this happened yesterday while I was sweeping with the large mop, a customer stopped me and told me that I had went behind him abruptly while doing the sweep, as its store protocol. But the thing is, I never noticed him. And I typically go around customers if they’re not in the middle of an aisle. However he came to me and complained that I didn’t say anything and said how he’s noticed how other courtesy clerks don’t say excuse me while doing the sweep. (Which I typically do IF I see them and I need to get past them.) I did apologize to him profusely, yet he still complained saying that I need to do a better job of it. And keep an eye on my surroundings. (Which I usually do.) But for whatever reason I never saw him. This whole interaction embarrassed me and is making me feel more self conscious about it, which is also encouraging me to keep a better eye on my surroundings.

So am I the jerk for not noticing him while I was doing my job?