Focus 2010 Auto Accelerator Delay

When I took delivery of my 2010 Focus Titanium 2.0 Auto in March the acceleration was sharp, but this has now developed into a distinct lag, but it is only apparent in low gear. For example, when slowing down to say 10 mph, then pressing the accelerator, there is a lag of a second or two when nothing happens, then it suddenly picks up and surges forward at considerable speed. This doesn't appear to be noticable when accelerating at higher speeds. I have to be really careful now when other cars are in front as there is a danger I'll rear end them. This also happens in reverse. I took it to my Ford dealer last March, they test drove it and found it to be normal. i was hoping to make it to its annual service, but I think it won't wait.