Disappointed

I am disappointed in my two canine charges this morning.  Cooper and Lola are both rescue dogs - an English Springer Spaniel and a German Shepherd-hound mix.  I've taken care of them for almost two years now, and haven't had many problems.  I walk them both at the same time, twice a day, for an hour.  They have a third of an acre for their backyard, and, while they do't have a "doggie door," in good weather the patio door stands open during the daylight hours, so the dogs can always go out to relieve themselves.  Lola also patrols the yard, barking at any incursions, and Cooper amuses himself chasing any airplanes that fly over (and we're near a small airport).  I haven't had any trouble with the dogs since my first visit.  (The three cats, while not angels, don't cause problems, either - other than getting Tipsi inside at dusk.)
   Last night, 30 minutes before the dogs' dinner time, Lola (the mixed breed) licked my arm, made eye contact with me, and promptly shat on the floor next to my chair.  I was amazed.  As soon as I realized what her position indicated, I yelled, "Lola! No! Bad dog!" - by the time I was on my feet, she had dumped everything.  It easily filled a 12-inch pizza box.  What infuriated, concerned, and amazed me was that the open door to the patio was less than ten feet away - she could very easily have walked outside, and relieved herself in the yard.  I picked everything up, and used Pine-Sol on the wood floor, then Lysol.  The doggies acted as if everything was fine and normal.  I took them out for their after dinner walk, and then took them out in the back yard every 90 minutes after dark, until I went to bed at midnight.
   I got up this morning, dressed, and went down to feed all the critters - this was at 5:20 this morning, I had taken the dogs out for 5 minutes at midnight - normally, I would just turn them out, but we've had a mountain lion in the area, so I went out, also.  I stepped into the kitchen and gagged.  There were two more huge piles of dog poop - one beside each of the food bowls, on opposite sides of the kitchen.  I turned the dogs out, cleaned up the mess, and then fed and watered everyone.
  I'm just trying to figure out why the dog(s) are suddenly having "accidents."  I'm their usual pet sitter.  Their food, treats and schedule has not changed.  Yes, Len and Susan were gone, but that's when I come to care for them...  Ah.  I just had the light bulb turn on over my head.  -  Shirley isn't there.  Susan's Mom lived in the downstairs apartment, and the dogs always ran down and visited her several times a day.  Shirley passed away in July, and this family trip was to take her cremains back to New York.  -  That's the big change...  I'll have to let Len and Susan know,,,  I wonder if they've been "having accidents" with their parents there?   I'll inquire when they return tonight.