Is this normal or should I be worried?
The black mark is the result of a careless plumber nearly setting the kitchen on fire when installing that cutoff valve. If your place hasn't burned down by now, you can ignore the burnt spot.

The green discoloring is oxidation caused by a slow leak higher up on the pipe. Tiny leaks sometimes seal themselves via corrosion, so if you don't find any moisture on the pipe, this is another thing you can ignore.

If you want more peace of mind, you could clean the green oxidation from a visible section of the pipe and see if it reappears in a few weeks. Clean pipe = no worries.

If you want less peace of mind, consider this: if the installing plumber was careless enough to burn the wooden cabinet with his torch, and to leave a leak causing that much visible corrosion, what else might he have done incompetently? You may have sloppy plumbing throughout your house.

Welcome to your new home, and good luck.