I think your photo turned out just fine, Tony
That said, I've had metering problems before with bright red flowers that fill the frame, using both centre-weighted and matrix metering. I also find that my later Pentax cameras (K-5 onwards) have a tendency towards over-saturated and magenta-tinted reds. I'm sure this is the case for the K-50 too. When I worked on producing a K10D "CCD emulation" Lightroom preset for my K-3 images, one of the things that involved was de-saturating the red channel and moving the hue towards orange.
As @mikesbike advises, the "Natural" custom image setting is a good choice for these situations. And if you have the flexibility of changing hue and saturation of red in your post-processing software, try adjusting that as I've mentioned above.