Ceiling Cracks

I inspected this home in September. 1965 rambler, hand framed 2x6 rafters and 2x4 ceiling cords. At the time of inspection house was vacant. Newly painted walls and ceiling. No cracks were observed to the ceiling. Yesterday the client called and wanted me to look at his dining room ceiling. Multiple cracks throughout the room. I have to believe these cracks have been around for some time and the past owner did a quick patch job to disguise them. Client was with me at the inspection and we both agree they were not present then.
Any ideals?

AC guy bumbling around in the attic. The cracks seem to follow the drywall joints.

No mechanicals in attic.

How about any other of the trades?
Those didn’t happen over night.

Those appear to be on the seams. From the way they look no tape was used on the joints, only mud. I would bet that the trusses expanded (truss uplift) and have opened up the cracks. These may go away come summer. That is my WAG for the day.

Looks like they did not use dry wall tape on the joints …

I agree with the possibility that no tape was used coupled with seasonal shrinkage of the ceiling joists. A day’s work for a drywall guy to rectify…

Earthquake, thunder? Poor tape job. Perhaps wrong size nails/screws used to install. May need some cross bracing in attic…