One thing I know about memeory that may be related: When you are in a depressed state of mind, it is easier to recall events and feeling that happened when you were feeling the same way, depressed. That is one of the ways depression grabs hold of you. You recall the past depression expriences easier and past happy experiences not so easily.When you are happy, it is easier to recall things that happened when you were feeling happy.
It also works that way with altered states of consiciouslness, like when your drinking alcohol, or sleepy.
So like if you studied for an exam when you had a fe beers, you may do better on the actual exam if you had a beer.
So, it follows that if your happy now, then depression happenings are harder to recall.
Or maybe we are all just getting old, lol.