The Germany international believes there were contrasting motives and events leading to both transfers
Bayern announced on Saturday that the Poland international has signed a five-year deal with FCB and will join his new club on a free transfer at the end of the season, making him the second Dortmund player to make the move to the Allianz Arena within a year after Gotze's transfer in the summer of 2013.
However, Muller does not think that the 25-year-old's imminent departure will anger the Dortmund faithful as much as Gotze's exit.
"I don't think he faces a difficult last few months at Dortmund. People already knew that he would leave BVB. It's not as emotional as with Mario Gotze," Muller told Bild.
"The announcement that Lewandowski will join Bayern did not surprise me. The transfer was to be expected.
"I don't know him personally, so I'll just let him surprise me. He has had a good season so far and I don't think that he will score less goals now all of a sudden."
Lewandowski has netted 11 goals in 17 Bundesliga appearances so far this term.