I would say so, yes. That is, of course, my own personal opinion. Others may disagree. I just think that, in that reunion scene, what reason would the doctor have to use modern slang? Especially considering that Sarah Jane herself wouldn’t likely use/understand modern slang in the say Rose/Mickey would, given the era she is from, and he would know it (presumably the writers too). And besides that, it just feels like using slang in that moment would be uncharacteristic for the Doctor, in such a quiet, emotional moment.