As far as all this race card crap, get over it and grow up, people. I'm sick and tired of people being called racist and prejudice just because their vocabulary isn't perfect.
Was it necessary to mention that they were Mexicans? No, it wasn't. Was it relevant to the story? No, it wasn't? But racist? Come on, get a grip.
I've been guilty of it myself, and many others I know (even some in my family at times), have been guilty of referencing someone's race when it is unnecessary. Such as "ya, I saw some black guy come through the checkouts at Walmart the other day..." when his skin color has absolutely no relevance to the story. It's more a force of habit than anything else. Maybe for those of you who have been brought up in the big city, where you see various races ALL THE TIME, it never crosses your mind what race a person is. But for some of us sheltered midwest, small town/country bumpkin hicks who aren't used to being surrounded by other races/cultures on a daily basis, it becomes more commonplace to notice someone's skin color/ethnicity, to the point where we note it when it isn't necessary. To be honest, I try to catch it in my own speech, knowing that it isn't the least bit important to the story that this person was black, or that that person was Mexican, etc, but for those who haven't got to that point yet, it would be nice if we could cut them some slack and not stereotype them as being secret KKK members just because their vocabulary isn't as enlightened and PC as ours is. I long for a day when race/ethnicity is as irrelevant and unnoticable as hair color, being right or left handed, etc. But as we continue to work towards that point, let's take into account that there are many people without a racist bone in their body who, out of force of habit, unthinkingly note skin color when it isn't necessary. There's no need to cut them down and belittle them as racists, and really no need to call them out on it....at least not in such a judegmental and confrontational way.
Of course, then there's other times when skin color IS relevant and it is STILL considered taboo to mention it. Like if there are 4 white people and one black person in a group and someone asks me "which one is Jill?" and I reply "she's the black lady". In that case, her race is the identifying factor in informing someone who she is, but unfortunately, there are still those who would think it's horrible that you just mentioned someone's race.
Really, people need to just get over it and quit trying to find predjudice in everything someone says or does. To me, to accuse the OP of predjudice, rather than giving him the benefit of the doubt that he is simply doing something out of habit is, in itself, a bit predjudice.