I'm no child psycologist, but my sister took a few classes and learned that if a child starts walking too soon, and doesn't spend an adequate amount of time crawling first, they are found to have a harder time in life with their 'reasoning' skills and making decisions! So there may be something to what your Doctor told you, that up-right position and then bouncing on their feet before they have spent enough time crawling, may cause a baby future problems, even if only in a minute way.
Doctors have to learn and know so much about everything.. I would listen to him if I were you, even if you can't find it to read for yourself.. just to be on the safe side. gezebel's kids are okay... except for that tick! ha!ha! That was funny. 
But not all kids develope the same. Personally I wouldn't take any chances against my Doctors field of experties. Take care.
