Definitely. My Nana was the best thing about my childhood - always kind, loving, comforting, stable. She read to me, made up stories that were the best and most thrilling there could be, took me on holidays, always had room for me in her big warm lap. I loved her so much and I still miss her and always will.
However, her relationship with her own daughter, my mother, was prickly at best. My mother had stories about her own childhood that I could honestly scarcely believe, about how she would walk in and ask with a child's innocence 'what's for tea' and be snarled by Nan - 'Shit and sugar!' 
I think when Nan had her own children she had a difficult husband, was trying to work several jobs, and had the house and children to manage too on little money. By the time she had grandchildren, her life was so much easier; she was happy and had time for and could enjoy the pace of life with a small child.
And when my grown-up mother had an accident and was helpless and bedbound for a while, my Nan stepped in and nursed her with all the love and kindness she hadn't been able to show when my mother was a child.
I'm so glad for you that your mother and your DS have this loving relationship. Her love for you comes out in that.