Originally posted by GlennG I second the suggestion from another, shoot the film and report back.
If the mirror foam is bad, cycling the shutter may fling black goo onto the focus screen and mirror that will be difficult to remove.
Yes, these degrade over time, whether the camera is used or not, and degrade more quickly if the air is rich in ozone. The seals and foam may be fine, but conventional wisdom is to check first if one has been made aware.
Edit: In regards to whether bad foams are obvious...sometimes yes and more often no. The easiest way to test is with a toothpick or similar wooden splint. Touch the light seals and mirror bumper with the toothpick. The material should be resilient and supple without being sticky or crumbly. If sticky or crumbly, that junk has the potential to make its way into the works of the camera.
Steve