Strange sounds from our air duct

Both of us were beginning to guess that our lake house must be haunted, and both of us moved here a few weeks ago! Then every one of us started hearing uncommon creaking & groaning noises at random times while I was in the day, then it was worse at night though & would, occasionally, wake us up.

It seemed as if the sound might be originating from the attic but it was taxing to pinpoint the origin.

I thought about calling out a clergy member but then a friend said he thought the sound might be coming from our HVAC system. After he said that, I did beginning to notice that every one of us only heard the sound when the heating system or a/c were on. Both of us rested a little bit easier after that but every one of us would still get creeped out every time every one of us heard the sound! Finally, I decided to call up an HVAC maintenance company to come & see if this was something they could take care of. The professionals explained that our air duct is loose & that the sounds were are hearing was just the ducts rubbing up against each other. They recommended duct sealing. I would try anything to get a fantastic night sleep again so I told them to go ahead, and last night was the first night every one of us all slept the night through. There were no more uncommon sounds coming from the attic… However, I keep finding myself listening for the creaking & groaning sounds. It is like I expect to hear it. I hope that too goes away after awhile now that the lake house is entirely silent now.
HVAC equipment