Since you asked, my two cents.
If something (easily correctable) bothers you during the beginning of a long term relationship... when every thing is new and exciting.... it will become more of an issue later on when things cool down to normal.
I'd do her a favor and mention it politely. If you can't talk about things as trivial as that, how will you handle the big deals?
Abigail van Buren
This is sensible advice. If it bothers you enough to bring it up on a forum like this one, it's not going to go away. And I can sympathize. I have met a number of women with admirable attributes whose language skills are compromised by stigmatizing usage. It would certainly bother me.
I'm an English prof who works with adult college students, many of whom are prone to similar fundamental errors in grammar and usage. Often, in business settings, this kind of mistake is noticed but deliberately overlooked, just as you have overlooked it so far.
You write that this woman "is very polished in her professional appearance and her communication," but given the basic grammar trouble that you have cited, I have to say that I'm skeptical that she is polished in her communication. This kind of error falls into a category of substandard colloquialisms and mistakes that many people make routinely, because no one has ever corrected them--and because many others who may have noted them (negatively) have been too polite or uninvested to mention them to her.
Anyone at any stage in life can improve her diction and usage, especially if she is making basic mistakes that she has simply ignored or not been aware of. You are in a position to provide her with some awareness--kindly and gently. The issue here is that the error in question is very probably not the only such error, and errors like this, in a professional situation, can prejudice a listener against a speaker in subtle ways that may never be discussed. I think she needs to know that you have noticed this small error and that she can, with no trouble, focus on eliminating it from her speech.