What is causing these hairline cracks?

We have a relatively new build house (now 8 years old) and over the years have noticed the odd hairline crack, which we have obviously put down to settlement as it was a new build. A little over 12 months ago we had a non load bearing blockwork wall removed between our kitchen and dining room. Our builder advised that no steel would be required as no load was being carried by what we were removing, and when the ceiling in this area was removed it was very clear that the joists were not supported by this wall as they ran the other way. It was tied to the external wall by a few wall ties obviously, but was not tied in to the other internal wall. Indeed, it really looked to be simply space dividing partition. However, over the last few months I have noticed more and more cracking, mainly at door heads, skirtings and windows, and would have thought after 8 years the house would have settled. Do you think the removal of a non load bearing internal blockwork wall would have had any effect, or is it more likely to still be settlement. Almost all the the hairline cracks are at first floor level, the worst ones being at the opposite site of the house to where this wall was, which seems odd.