should I replace the thermal paste on an old but unused CPU?

I bought a package of an old but never-used motherboard, CPU, and RAM that fit my needs. (And what a bargain, for only US$79. If they work.) The photos indicate that the CPU and fan have been mounted. (Unless I find that those are mere stock photos. Going to find out from the seller.) It just occurred to me that if the CPU and fan are actually mounted, the thermal paste may be dried up and needing replacement if someone mounted them years ago (must find that out as well). The board model is Asus M4A785TD-M EVO and it's about fifteen years old according to my research. I'd better make sure I have some paste.