I have many slim Asian friends who refer to their 'rice bellies'--the phenomenon of being slim all over, except for a little roundness in the tummy area. Now, to my eye, they have no rice bellies to speak of, but they did get me thinking about an anecdotal observation of mine.
I definitely do get carb belly. Generally, I see it when I eat over 120g of carbs a day, which can happen, since I set my upper limit as 150 (not counting fiber). My daily carb count can vary between 50-150g on any given day.
There is more leeway for carbs in my diet because I'm not trying to lose weight. Also, 150g of carbs generally means I ate more fruit, including dried fruit, than usual, or I had more chocolate than usual--not that I went nose down into a baguette.
In any case, I do notice a little belly when I hit my upper carb limit. Generally when I see the carb belly, I know it's time to take it down for a few days, and I'll usually go right back down to about 50g. 3 days of 50g usually puts my belly to rights again.
The other thing I notice with carb belly is that, per my trusty (and I say that with sarcasm, because I have no idea how accurate it is) Tanita bodyfat scale, my body fat jumps ~3 percentage points along with the carb belly. My theory, since the scale judges body fat with electrical impulses, is that extra carbs somehow screw with water retention, which in turn screws with the readings.
It's observations like this that reinforce how important what you eat is to how you look and how you feel about yourself. Oh, and that remind me to watch my carb intake ;)