Hmmm. I'm not sure. When I remarried, I had to show not only my original birth certificate, but also my divorce certificate - to show that the name in which I remarried was my name at the time.
I still use my original married name a lot of the time, particularly for work, but it does create complications since my passport (which is often used for ID) is in my current (2nd) married name - so I have to cart my marriage certificate about to show that Mrs X is also Mrs Y.
Didn't the registrar ask to see all your relevant documents, or did they assume that this was your first marriage?
I feel sure it will be OK, since you lost your husband as a widow rather than a divorce. Interested to know what others advise!