Is there any evidence that Lent used to be a 3 day observance?

I was taught that Lent represents the 40 days Jesus spent in the desert. However, in church on Ash Wednesday, my Priest stated that it used to be 3 days and was extended to 40. I can only assume that the 3 days were the time Jesus was entombed. Was Lent ever 3 days? Was this official doctrine? And if so, when and why was it changed?