Is it weird for my fiance to "WE" when he talks about his ex wife???

So my fiance always says "WE" when he talks about his ex wife. He'll say we did this we did that when he talks about his ex and him. They have a daughter and my fiance and I have a 7 month old daughter together. So when talks about his ex's daughter when she was a baby he says we bought her this we did this when she was teething. Me and my fiance have been together 2yrs. Him and his ex were together 15yrs. Is that normal? When I tell him he used we again he corrects himself