earthfriendly wrote:The ex-owner (of our present home) tried to cover up areas of imperfection on the wall with the original paint and you can see where he desparately
tried to do the patching. Paint, even when kept in its original can, deteriorates over time. We ended up just painting the entire room.
For the OP's case, it is a tiny patch and you can google on brush stroke techniques on how to camouflage it.
While there may be some separation of paint kept in an airtight container, this can be remedied with thorough stirring or shaking.
As long as the inside of the paint container has not rusted, the paint should be OK.
Usually it's the colour of the paint on the wall that changes with time (e.g. fades, etc.), due to exposure to light and other elements.
Using a "dry brush" technique to "feather" the edges gives a more gradual transition that is harder to detect.