Hi Happygran1964. First of all, congratulations to you on the birth of your grandson.
I do feel, and was in a somewhat similar position to you when our first grandchild was born. I was very excited, normal! but my expectations of meeting my granddaughter were not met. My husband reminded me that it’s an emotional time all round and that our dil and son were probably all over the place and to sit tight. At the time I didn’t take very kindly to his advice ( too many emotions!), however in hindsight and following his advice I was rewarded when I met my granddaughter two weeks after she was born.
I really just think they ‘don’t think’ about it.
Think positively, offer to be on hand if they need shopping or washing done ( boring I know) but try not to be too disheartened. If you sew/knit use the time to make something special. Carry on with your own life, meet up with friends for a coffee or lunch, don’t be sitting around and be waiting for the invite, you will feel better if it comes when you least expect it.
They will appreciate all you will do for them in the future and you will have a relationship with your grandson and be glad you ‘waited it out’.