So, you cooked the oats before putting them in your shake?
I blend mine, uncooked. Of course, the blending cuts the oats down into a finer material, which will alter affects on insulin and such (more surface area - quicker digestion).
Side note: One time I decided to try the oats unblended in a PWO shake. After my workout, I got in my truck and took a big swig of my shake. As soon as the whole oats hit my mouth, I threw up everywhere! I can't drink stuff that has that kind of texture, especially after a workout.