Is the short sermon delivered by the Imam after Fajr prayer considered an innovation (bid'ah)?

Disseminating knowledge is among the most virtuous deeds and the best acts of drawing near [to Allah], and it is not an innovation. It is preferable for the Imam not to initiate the sermon until the congregants finish their glorification (tasbih) and the latecomer completes his prayer, unless he fears that the congregants will leave, in which case there is no blame upon him.