Push Gas Pedal and NO GO!

As much as I don't think my "technical" jargon can communicate this problem effectively, I doubt that I'm the only person to have expireneced this so I will try and explain.
Backround
I have an 08 Touring Prius that I've owned since mid-Jan. Currently 9800 miles (I commute 100 miles/day 90% hwy) and this happened this morning on my morning commute. I'm averaging 50.0 mpg lifetime and about 55 since weather warmed up. This morning was about 50 F and this incident happened about 25 miles into my commute (car was plenty warmed up)
I have a 3-4 miles stretch where I cut through a town and the speed limit is 30 mph (I glide or electric 95% of this). At the end of town, I merge (ramp) back onto a state hwy and the new speed limit is 45.
Problem
As I merged onto the hwy, I was still electric only (30 mph). When I saw my opening, I pressed the gas pedal approx. 1/2 way to accelerate to 45 and ease into the opening. The car just stuttered, a fast repeated stutter! The ICE didn't come on. No acceleration just thunk, thunk, thunk, thunk for about 4 seconds (I had my foot still pressing the gas pedal). I released the gas pedal, the car went into regen mode and I pressed the pedal again. The ICE started normally and I accelerated up to the speed limit (the drivers behind me were none to happy). The rest of my commute was normal.

Was this an exception? Does this happen on occasion and therefore might be "normal"? I went to college for mechanical engineering and I have good handle on the ICE but admittedly accept that I don't know enough about the hybrid system to "know" about this.

 

No, I very familiar with this hesitation. This was very pronounced.

[/quote]I'm wondering if your half-power request was hovering on some sort of a threshold, causing the ICE to come in and out. I would have expected enough hysteresis in the control loop to keep that from happening, but it is possible. If you feel that again, try giving it more gas and see what happens.[/quote]
Good suggestion. If it happens again (I hope not), I will try more gas.

[/quote]It's also possible that you are having engine trouble. While very reliable, a misbehaving ICE could produce the symptoms you describe.

Tom[/quote]
I would expect some "idiot" lights to have shown up or stayed on and I had none.

Thanks for your response.

 

No, road was dry but the idea of the traction control is interesting. I have never had the traction control kick on before so it is possible. Is there a better description of how that feels?

 

I didn't notice any loose stones but this time of year, every shoulder of the roads here are covered in sand put down from winter.
It sounds very plausible that my traction control engaged. I managed to get through the winter without it but I used it in the spring!