Is it possible for an esr (erythrocyte sedimentation rate) to rise to 60 and return to normal for no known reason (including no evidence of an infection)?

This would be unusual. If it happened over just a few days or weeks, probably the test was flawed. However, it certainly is possible to have an undiagnosed inflammatory condition that would be active (or a chronic condition with a flare-up) and then resolve over several weeks or longer. Discuss with the clinic or doctor who ordered the test. Good luck.