Anyone had problems with the GSI deck grips delaminating ?

yes, but a good few years ago. How old is the board?

Brought it second hand only used once.I paddled it 10 times on flat water & grip starting to delam??

Had delam problems a few years ago, some manufacturers were using a pad where the raised parts seemed to be laminated onto the base but they would peel off if you looked at them!

Only option was to take off the old pad and replace it. You'll find some good advice on how to do this if you search.