91 year old with dementia suddenly mobile. Is this a phase or an indication of something worse on the horizon?

My godfather has been living with me for the past year while we care for him and his dementia state. He is ambulatory with a walker but has always needed help dressing and walking around. His bed is a hospital bed with bars meant to keep him safe in bed at night. He has not been able to get out of this bed on his own for a year. This morning, we wake to find that not only did he get out of that bed, but was completely dressed in a button up shirt (all buttons buttoned perfectly) sweat pants ( he went to bed in a diaper) and shoes that were TIED and he was on his way out the back door before we knew what happened!! Is this a phase or an indication of something worse on the horizon?