I know what you mean! I am very well known for eating things I see without even thinking about it. It happened when I was first diagnosed and now that I've been gluten free for over 5 years, I slip up thinking everything is gluten free.
I'm really bad about asking for no croutons on salads. All the salads I eat never have croutons on them so I just forget that other people's do.

It's a good thing I have my husband to watch out for things like that!
Feel better!