Is there any evidence that Montressor premeditated Fortunato’s murder?

There is a great deal of evidence to suggest that Fortunato's murder was premeditated.  In the first line of the story, the narrator and murderer, Montresor, says that when Fortunato insulted him, "[he] vowed revenge."  This certainly suggests that Montresor conceived of and planned the murder in advance.  He also says,

It must be understood, that neither by word nor deed had I given Fortunato cause to doubt my good will.  I continued, as was...

There is a great deal of evidence to suggest that Fortunato's murder was premeditated.  In the first line of the story, the narrator and murderer, Montresor, says that when Fortunato insulted him, "[he] vowed revenge."  This certainly suggests that Montresor conceived of and planned the murder in advance.  He also says,

It must be understood, that neither by word nor deed had I given Fortunato cause to doubt my good will.  I continued, as was my wont, to smile in his face, and he did not perceive that my smile was at the thought of his immolation.

Here, Montresor claims that he has continued to pretend he is friends with Fortunato, never revealing that he is, all the while, planning the man's total destruction.  

Furthermore, Montresor has with him a "mask of black silk, and . . . a roquelaire," or long cloak, with which he can hide his identity from anyone who might see him with Fortunato.  In addition, Montresor told his servants that he would be gone all night and that they should not leave the house, knowing full well that this would "insure their immediate disappearance" as soon as he left.  In other words, Montresor has thought to bring a disguise and has made sure that the house would be empty; this shows forethought.

Finally, Montresor also has, hidden beneath the folds of his cloak, a small trowel, precisely the tool that one would use in brickwork (and he is planning to wall Fortunato in).  All of these facts show that Montresor did plan this murder beforehand.