It only takes one or two strokes on the strop accidentally lifting the spine instead of rolling the razor ON the spine,to dull your edge.Sounds like this may be the case.You may be able to get it back with quite a bit of correct stropping,if you don't have a pasted strop or hones.Or,if it's too bad,you may have to send it out to one of the honemeisters in the classifieds for a pro-honing.