My small roses have suddenly shown some problems. I recently transplanted them in a bigger pot, because they looked quite cramped in the old one. It's been very hot this days, so I am wondering if it's a problem of sun, watering or potting mix.
I'm presented with what looks like two completely opposite issues - the flower has suffered balling, and that is usually caused by damp cool conditions, in particular, rain, but the leaves appear to be suffering from drought/heat. I suppose there might be an explanation - perhaps, when you watered these in to their new pots (and I hope you did) you watered the flower as well. If that flower was present when you repotted, it won't have liked the change much - trim the flower off as if you're doing normal deadheading, and if your plant has been exposed to full sun all day long, provide some shade during the hottest part of the day, and increase watering.
The discolored leaf tips may also point towards a nutrient shortage, but because of their bleached, faded appearance, I'm assuming the cause is, in fact, insufficient water and/or hot sun.
UPDATED ANSWER: Yes, trim the ruined flower off, as I said, as if you were doing normal deadheading, it won't recover now its balled. Doesn't sound as if its hot sun causing the bleaching at the tips of the leaves then, but, on the assumption the pots have open holes in the bottom and water isn't then trapped in any outer container, or if it is, you empty it after 30 minutes, increase watering - if more brown/bleached tips appear as time goes by, post another photograph so we can try to work out what the nutrient deficiency could be, although, to be fair, a dose of rose food now wouldn't do them any harm anyway.