Its normal for your temp gauge to read higher after you shut down... your
fan blade  has stopped & coolant is no longer circulating .Any residual heat
trapped in the block is being soaked out.
You can try raising idle up a little for a minute ,then shut down and see if
that helps.
I was running a brand new John Deere excavator last week and I needed to
stop for fuel. I idled for a 1-2 minutes to cool the turbo, then shut down.
After I
finished the fill-up,I restarted it and the temp warning light was flashing
and the temp gauge was pegged. It only took 30 seconds for the temp to drop
right back to mid range after hitting the key.