I keep dreaming about my dead dog

My dog (penny) has been dead for over 10 years, yet the past year or so, I keep having dreams that she is alive again. In my dreams, I always realize that it's odd that she's back from the dead, but I just sort of shrug it off and enjoy seeing her again however in each dream, I know her visits won't last long because I know she is old and going to 'die' again soon.

I just don't know why all of a sudden this past year, I keep dreaming about her coming back to life. She was my first pet and I still get teary eyed when I think of her.. but I have had two more dogs since she passed away and I just don't understand why I keep dreaming about her a lot lately. I know there are some that say one's spirit often appears to them in their dreams after they die to let them know they're ok. But 10 years later? I just am a little baffled at this.

Any thoughts?

It does seem that the dog's spirit is still there.
You must have really cared for the dog a lot.
I would be happy to have a dream of one of my previous pets.
There is one dog from my past that had to be put to sleep.
I miss that dog a lot. I only wish i would dream about him.