Over the years I've noticed that an off-value resistor can be significantly impacted by the heat of the unsoldering to take it out of the circuit. 

Usually the heat makes the out-of-tolerance resistor get better for a while, but in a few cases the warmth made it worse.  

For me it didn't matter - I could not trust that resistor and it was headed to the trash either way.  But this might give us some insight into the problem.