Engine stuttering or hesitating at highway speeds?

Hi there! I just got my new 2013 Persona Prius on Saturday. I haven't put too many miles on it (under 200) but I'm noticed that a feel a stuttering or hesitation when I reach highway speeds. Typically about 65 -70mph. I can't think of a better way to describe this but it feels like the when driving a manual transmission, when you need to shift to the high gear? That kind of stuttering feeling. I'm sure that it's not the same problem but it feels like that. Once I go faster, the feeling stops. Or slower. But going between 65 to 70, it's the same feeling.

I stopped by the dealership tonight on my way home and one of the mechanics rode along with me. Of course, I couldn't get the feeling to happen. Figures, right? But they offered to drive it tomorrow and test it again. I was originally thinking that it was the tires but it really doesn't feel like that. I had a 2010 Prius before getting this one so I have an idea of what the ride should feel like. I don't remember my old car feeling like this.

Any suggestions? I'm hoping that the dealer can help tomorrow.

 

I just wanted to update on my problem. I should say that I made some errors in describing the original problem. After driving it more, I felt like the issue wasn't the engine or anything mechanical, it felt like a vibration that came from the floorboard. I noticed the vibration on the seat and going up my legs.

I left the car at my dealership today and they called me to tell me that two of the tires were unbalanced. The technician drove my car before doing anything to it and could feel what I had mentioned. Then found out about the two tires being off balance. He fixed those and then took another drive to the same place to see if it happened again. It didn't so he figured that must be it.

I drove around today and went to the areas that I remember it being very noticeable. So far, it's gone! I'm really relieved. I just hope that it stays that way.