Is the dog OK with being left alone/being away from her? I would imagine guide dogs more-so than most service dogs are with their person ALL THE TIME so I would be more concerned with that than anything else
Yeah, guide dogs are with their person all the time, but they're actually usually less attached to their person than other service dogs. Most guide dog training organizations don't really stress relationship building.
(I've discussed this particular subject with trainers from multiple organizations.) Plus guide dogs are supposed to be pretty independent, they're supposed to follow environmental cues rather than cues from their handler; for example, when the handler says "walk forward" and there's something blocking the path, the dog is supposed to disobey the handler's cue.
Compare that with, for example, medical alert dogs, who pay constant, close attention to their person, looking for any tiny changes that cue him to a problem. These dogs would have more of a problem being away from their person.
But of course, good assistance dog trainers will practice separation periods with the dog for instances just like this.
Also if the guide dog came from an organization, remember that he lived in several different homes in the first couple of years of his life, so he should be quite good in a new home.