am I losing brain cells or am I just stupid?

Had one of those old women moments today, not only did I forget the speed limit of the road I live on, i was doing 30mph on a 40 road and was wondering why everyone was getting away from me! I also had to come back in the house twice cause I kept forgetting things, one of them being the folder for college - the only reason I was leaving the house and the main thing I need for college. But worst of all I tried to lock the door with my car key thing, what I mean is I actually pointed the key at the door and pressed the door lock button. Yes, I am that dense!
Is this all a sign of a developing problem, am I finally hitting old age?

Speaking of old age, I think I am getting away with the 25year old in a class of 16/17yr olds, I don't think any of them know still. I have ahd to watch myself, and not say things like "I was 18 when that film came out..." when everyone knows it came out in like 1999.

My piece of advice for a week - if you are going to make a Christmas tree out of A1 size card, don't think it will look symetrical if you draw it by hand, draw one side, cut it out then fold the card in half and use the outline of what you have done to draw the other side. Oh, what a random life I lead.