I noticed that I do forget a lot of the stories I used two years ago. Depending on the kanji, I usual pass it (if it;s something I see a lot/common). But if not, I fail it/re-learn it. But I'm noticing that most kanji I can remember but not the story. That means that my mind is becoming used to Japanese. But this is usual if you've been doing RTK for more than 1 year(all cards mature)

Mmm... I think heisig himself mention in a chapter what is happening to you and he stated that there is nothing wrong with that. Eventually you won't need a story to remember each kanji, as you get more and more expose to native media you are going to recall them without the story.

I note that this happens to me specially with the easier kanji like the numbers and also some other kanjis that I've saw many times in manga books.

The story is a device to help you remember. If you don't need it to remember then I think that's fine.
My goal is to remember the Kanji. If a keyword comes up and I can produce the kanji then I pass it. It doesn't matter how I managed it, I still got it right. Sometimes I need stories, sometimes not. I wouldn't worry too much. The SRS system will keep you right anyway.

You should read the preamble to chapter 31, where Heisig describes how the story slowly becomes irrelevant.

There is yet a fourth stage to be reached, as you have probably realized by
now, but one you ought not trust until you have completed the full list of the
kanji given here. In this stage, the primitive elements are suggested according
to form without any immediate association to meaning. Quite early on, you will
recall, we insisted that visual memory is to be discarded in favor of imaginative
memory. It may now be clear just why that is so. But it should also be getting
clear that visual memory deserves a suitable role of some sort or other, once it
has a solid foundation. This is a process not to be rushed, however appealing its
rewards in terms of writing fluency.

He does caution against relying on visual memory too much, but basically this is expected and should become more common as you go on.

I'm only at 350 at the moment, but from the start I've thought that the stories and perhaps even the keywords are like "stitches" that tie the kanji to your brain. it's okay if they fall by the wayside. the eventual goal is being able to write the kanji based on the keyword and if you can consistently do so without thinking of a story you're doing very well.

Just as Heisig says though, you should be careful. it's easy to overestimate how strongly the flesh has fused after the stitches disappear. while learning more new kanji and making up more stories you can get confused with earlier kanji.

tl;dr when that happens you can click you remembered it, but refresh the story afterwards if you haven't finished rtk1 yet.