Reskimmed brick wall, hairline cracks

[MisterBoy]

I recently stripped all the wallpaper in my 1860s living room, every wall is solid brick. I had a plaster come and skim all the internal walls before we painted them, but I've noticed a couple months on there are a few hairline cracks appeared i the new skim/paint. They all seem to be from the corner of doorframes up to the ceiling, kind of diagonally up.

The house has no known movement issues (I've been here 10 years) so I'm wondering what would cause this and if there's anything I can do?
I did the same in two other rooms and I haven't noticed this issue in those rooms at all.

 

[oliverwilliams18185]

Diagonal hairlines off doorframe corners after a reskim are almost always the skim drying out. The house is not moving. Old brick with lime mortar moves a fraction with the seasons. New skim handles that worse than the old plaster did. The pencil and date trick is the right call. If the cracks do not grow in six months, fill them, paint, and forget them. Still get the plasterer back for a look. A decent one comes back and sorts hairlines as goodwill. And you want it on record that you flagged it early.