Congratulations on taking a risk to get your product out there! There are many opportunities out there that some businesses don`t, or can`t afford, to take advantage of. The WBDC has obviously been a good resource for you.
As far as a Thank You. I recommend sending a nice note. The odds are that she won`t read it but her assistant will. What I really recommend doing is to also send a press kit on your product/company to a producer at the MS show with a pitch letter regarding your business and the hope they will contact you when planting season starts. If you have something relative and timely now, in the next few months, (i.e. people are sitll planting somewhere, or just to pitch for spring), add that into the mix. Don`t be afraid to mention that MS received a WEDGIE when she was in Chicago last.
Go for it! This is a great chance for you to potentially be on air, or more importantly, have your product on the show.
Feel free to contact me if you have any further questions.