I have had this on my cabbage pink spring bloom only but the cause I found out (been a few years ago) was over fertilizing before spring blooms. If I don't fertilize it before it blooms it is just fine. I also have what appears to be the same old garden rose you have there and I have never seen it do this till this year and the temps were all over the scale and I over did the fertilizer and it is doing this. It is on it's 3rd flush and now some are like this and some aren't . Doesn't seem to hurt the rose just looks funny:).
