theThe maximum operating temptaturetemperature of the raspberry piRaspberry Pi is 85 celcius and raspbian85°C so 40-50°C is probably OK.
Raspbian shows a thermometer in the corner of the screen when the raspberry piRaspberry Pi reaches 80 celcius and that thermometer80°C which slowly fills up until the raspberry piRaspberry Pi reaches 85 celcius so 40-50 celcius is probably ok85°C.