Should I worry about WD REDs running 40C on a mostly idle machine?

I have been reading here that disk temperatures should be under 40C. Mine is a home server setup with me being the single user (mostly), and the system is idle lot of the times, but the disk temperatures always seem to hover around and sometimes above 40C. That's probably partly because I live in a tropical country but the room temperatures are nowhere near that. My guess is that its because the disk is always spinning.

The server is mostly read from over a single 1Gbps link, and...

Should I worry about WD REDs running 40C on a mostly idle machine?