Ceramic capacitor value changes after soldering!
The only clue I can find might be this: -



It looks like you are seeing a +16% shift in value and X5R is not known for the greatest  dielectric so this may be counted as some form of initial aging due to soldering. After all, it started about 8% down and it's gone 8% over. I'd expect X7R dielectric to be better (stabler) and C0G/NP0 to be better again.