Your grandfather may be more of a hypochondriac and be seeking attention and sympathy by pretending to by sick all the time rather than actually having Munchausen’s. You haven’t given a lot of information or any of his history in your details.
Munchausen is a pretty severe, chronic disorder. People with true Munchausen’s generally take things quite a bit farther than merely exaggerating symptoms. They will actually infect themselves with bacteria and cause self-inflicted wounds. As your link states:
Patients with Munchausen syndrome may simulate many physical symptoms or conditions (eg, MI, hematemesis, hemoptysis, diarrhea, FUO). Their abdominal wall may be crisscrossed by scars, or a digit or a limb may have been amputated. Fevers are often due to self-inflicted injection with bacteria; Escherichia coli is often the infecting organism. These patients initially and sometimes chronically become the responsibility of medical or surgical clinics. Nevertheless, the disorder is a mental problem, is more complex than simple dishonest simulation of symptoms, and is associated with severe emotional difficulties.
Also, as your link states:
Diagnosis is based on history and examination, along with any tests necessary to exclude physical disorders. Less severe forms of factitious disorder may also involve the feigning of physical or mental symptoms (eg, depression, hallucinations, delusions, or symptoms of posttraumatic stress disorder), with an apparent goal to assume the sick role. These forms are not considered Munchausen, which is more severe and chronic, with recurrent hospitalization, peregrination, and pseudologia fantastica (lying in a manner that is intriguing to the listener).
Repeated visits to doctors, emergency rooms, repeated hospitalization, those a key symptom. People with Munchausen’s don’t just or even really, want the attention of their family’s they want the attention of hospital and medical personnel.
Does you grandfather have any of those symptoms? Do you think he has ever deliberately harmed himself in order to make trip to the hospital necessary? Does he have a history of frequent, repeated trips to the emergency room or repeated hospitalizations? Repeated surgeries?
I’m not psychiatrist or psychologist and am no expert your grandfather could possibly be exaggerating his symptoms and not taking his meds for attention. That doesn’t mean he has Munchausen. Maybe he’s just getting old and he’s lonely and wants some attention and wants someone to be concerned and say things like “Grandad, you have to take your medication! We care about you and want you to be around as long as possible!”
Here’s the wiki on factitious disorders