Why would activity suddenly stop?

There's a long running "joke" that my grandparents' house is haunted. The place often gave off an uneasy feeling, but not always. Little odd things would be blamed on "Mr Hoag" the late husband of the woman my grandparents bought the house from. He died of a heart attack during construction, but nowhere near the grounds.

It was mostly sounds, occasionally movement. My mom told me when she was recovering from a C-section, she was staying in what would later be my room. My grandparents had me and my new brother down at my uncle's. She said she heard someone walk down the hall and saw the door knob turn. She called out "Dad?" And the knob sprang back into place. She hobbled out of bed as quickly as she could and found the house empty.

Another time we were all out by the pool when she swears she saw someone walk past the living room windows.

My brother once heard boots following him as he went to the bathroom.

Another time after grabbing after school snacks my brother and I headed toward my room. For context the hall is L shaped and goes: bathroom, master bedroom, my room, and grandmother's room. As we turned the corner we saw the door to my grandmother's room just slowly opening. For whatever reason, my reaction was just to reach over and pull the door shut before we hightailed it into my room. My grandpa told us it was just suction, but generally another door in the house has to open or shut to create that suction (and in my current house that results in doors slamming, not slowly opening). My grandmother was equally dismissive.

My last experience I was sitting in the living room with my grandma, watching TV. Suddenly it sounded like a mop or broom was knocked over in the pantry. I looked that way and my grandma just blurted "I didn't hear anything." I got up thinking the cat, or possibly something the cat brought in might have knocked something over. Nothing was out of place and there were no critters around. I mentioned it to my mom and she complained that similar things happened the last few times she visited.

Not long after, my grandma who was already suffering from early dementia, fell and broke her leg. She was in the hospital and the a rehab facility for nearly six months. Her dementia got much worse during that time. She still remembers everyone, but her short term memory is pretty well gone and whether or not she can hold a conversation depends on the day.

A while back my mom asked me if I was still hearing stuff moving around up there and I said no, last few visits have been quiet. She said she hadn't heard anything either. It's been a couple years now with no more sounds or even creepy feelings. The house used to be so unsettling at times that I was terrified of moving into my own place. Yet, when I did move out I wasn't at all scared to be alone anymore. I even walked out into my wooded backyard in the pitch black to call for my cats sometimes with little worry. When I mentioned the lack of sounds to my grandparents, my grandpa just scoffed, saying "you're in a trailer. Brick houses creak and settle." About five years later me and the hubs moved into a brick house. It settled once during our first winter there and it just made one loud pop and we found a bit of a gap the next morning. As seasons change doors will start to stick, but there isn't constant creaking or shuffling.

I'm still not real sure what to think of the whole thing. I'm just curious what this sounds like from an outside perspective.