Whether or not the people described in the poem are behaving irrationally depends on what you define as being irrational behavior. Some readers of the poem would probably say that yes, their behavior has no rational basis. They have no logical reason to fear that anything or anyone might be in the house, since it has been locked while they were away and is cold, dark and quiet when they return. This being the case, they do not need to be taking the precautions described in the poem.
Other readers could argue that the people are behaving very rationally and reasonably. They've been gone far away for quite some period of time and are now returning in the night to a location where apparently they had a frightening encounter or occurrence at some point in the past. Given that history, it is logical to attempt to prevent another upsetting episode by making noise upon their arrival and during their entrance, leaving the door open and accessible so that any unwelcome presence has "time to be off in flight" before they enter the house and light the lamp.