It's really more like general "state or mood dependent memory"
When a person is happy...the memories they tend to call up are happy ones.
When a person is depressed...all they can remember are the dark times, the bad moods. It's like the current mood state facilitates retrieval of mood matching memories.
It can even generalize further...if you experienced something while in an altered state: drunk, high, excited, afraid...you'll remember it better when in that same state.
And anger being SUCH a physiologically arousing emotion we can easily have neural excitation that triggers memories of old hurts, other things to be angry about.
For the genuinely curious:
Did you know that ANGER is processed in the left Frontal areas of the brain, along with positive emotions like happiness, excitation, joy, anticipation?
These are collectively "approach" type emotions. All of them involve slight increases in brain temperature.
The right Frontal areas process the more "avoidance" type emotions: anxiety, dread, despair, sadness.
Oh boy, been out of the lecture hall too long. Now I'm lecturing on the bb!
