Can MMP rate change at check-in?

I am a new Marriott employee using the MMP for the first time next week. I got a steal and was able to book a week at the Fairfield Inn next to Disney Springs for about $500. I booked it about two months ago, and the reservation is confirmed. I'm now seeing on the website they're charging almost $150 a night, I'm just wondering if they can change the rate at check-in? Because I can afford the $500 but if I were to have to pay almost 2000 I couldn't do it. I feel like it would be shady, to change it and check in, but wanted to see if they had happened to anyone else or if they honor the price.