You need to post your question on the main rose forum.
This forum is for posting your rose pictures.
Your get a lot responses on the main forum.

It does not look like the beginnings of blackspot, but, I can't be sure from your pic. You need to take a close-up of the leaves in question.
Are those rocks or wood around your roses? Rocks reflect heat and are not a good idea for placing around plants.
If it's wood, your fine.

Here is a link that might be useful: Main rose forum

Looks like yellowing leaves from too much water, maybe? A heavy mulch retains moisture underground and this little guy may be getting too much moisture....

Here is a link that might be useful: My Garden Blog