I think she is saying that you will lose some interest in the next 6 months for multiple reasons...
1st, as you stated, the $8k credit is bringing a lot of people and interest to your house, but it expires in November, so what then? You'll lose out on quite a few potential buyers...
2nd, its nearly winter time which has always been a slow time in selling a house, so be prepared to sit tight until next March/April probably if it doesn't sell before November.
3rd, the interest stuff is REALLY unstable at this time because of the economy and the fed pumping money like its their job, therefore if come spring time home mortgage rates have gone up 3%-4% to 8/9/10% interest, you'll have even less potential buyers available to you because they suddenly can't afford as much house anymore...
You have to figure out what is worth it to you, but if you're paying $1300/month to own a house you don't use/don't want, and have to hold it until March to sell it, you've already pissed away $7800 in mortgage payments during those 6 months plus something could break/whatever and you would have to pay for that as well. That's not including taxes/insurance on the property if not included in the $1300/month. It very well could cost you $10k + to own that house for the next 6months, whereas you certainly won't see an improvement in value of $10k in that short period.
Just my .02...hindsight is always 20/20, and I know that I've missed the boat before by refusing to a quick sale for slightly less than I want, and then having to take that much or less later down the road.
Good luck.