WD PR4100 Operating temperature

When I look at my drives temperature they are consistently above 40 C, should I be worried ?

I see Fan speed as 540 RPM and it running fine.

You need to post in the sub-forum for your device. Have you tried to locate the User Manual for the PR4100?

https://community.wd.com/c/network-attached-storage/9

User Manual
https://support-en.wd.com/app/products/product-detail/p/139