Ramadhaan & Fasting

Fasting on Mondays

Q: An Aalim says: Traditional Eid-e-Milad-Un-nabi is Bid'ah. It is not Islamically right. But, it is true that Rasulullah (Sallallahu Alayhi Wasallam) himself celebrates the days Modays keeping Fast since it was his birth day, day of Hijrat, day of getting Nabuwat etc. I would like to know, if it is correct and if so, can we keep fast on Mondays like our prophet (Sallallahu Alayhi Wasallam)?