It's a scary thought that you might be starting to lose bits of your memory and undeniably it's a hard thing to come to terms with the fact this may be happening to you. However it's also difficult for loved ones to cope if you as a person refuse to acknowledge the possibility of this.
The sad fact is that dementia cannot be cured but it can be slowed if caught early enough: the even sadder fact is that most people will not accept this could be happening to them and crucial time is wasted.
Personally I worry that my mother sometimes forgets how the door locks or how a remote control that she has used for years works but she is adamant there is nothing wrong except old age and getting slower; as such no help can be forced upon her.
If you are worried about a loved one then I hope that you are able to talk them into getting some help and there is always the National Dementia Helpline if you feel that you have more questions or to better understand Dementia.