For a mom with her hands full of kids or someone who is elderly or disabled, I might agree to keep an eye on a bag if they asked nicely. However, the very way the woman in the OP acted was not only outright rude, but suspicious...like she's trying to make things move so fast that the OP wouldn't have time to think or say no. From the way it ended it sounds like she was just self-entitled and etiquette impaired, but initally, I almost wondered if she didn't see a security officer approaching with a K-9 unit. "Oh, shoot, the dog's going to sniff me out! Quick, make it look like this bag isn't mine!"