OK, my TWO year old is 37lbs and 37.5". She was 2 in May. The ped isn't concerned, given her height - her brothers are also big kids but very proportional. If your kid was at 90% in weight but only 10% in height, sure, there might be a problem, but as mentioned above, you have to look at both percentiles. I'm very tall and of COURSE my weight would be overweight for a woman 5'0" - but I'm 5'10 and that's what they need to use to calculate proportionality.
Further, at 4, my 2 boys had not completely gotten rid of their toddler chub - at 5 and 6 they have really leaned out. That may be something to consider...but as long as she's eating a healthy diet, I wouldn't put too much stock in any dire predictions about her weight.