IMO rude would be if she or someone said "that's a lovely sweater, but why did you make in that color? It looks like baby puke!" Or "have you gained a little weight your new sweater is a bit snug?"
If she's pulling the garment off your body to try it on that's rude, but asking because she likes it should be considered flattering even if its annoying. If she didn't like it she wouldn't ask.
Strangers or even family who don't knit don't realize the amount of time, work and money is involved in a hand knit or crocheted object. They really aren't being intentionally rude to ask. The rude comes in when you tell them what you'd charge and they say its not worth it. So my motto? Just say no.