I was holding a load of logs from falling with my arms when my right arm just gave way. I ruptured the biceps tendon. I've been on the job 22 years and have never seen anything like this. Am I a fluke of nature or what?

Biceps tendon rupture isn't rare but it is uncommon. The dominant arm is usually injured. Men in construction or heavy manual labor are affected most often. They are often in their 40's and smokers. Nicotine has a known effect on bones and muscles.

It sounds like you have two of the three most common risk factors for this type of injury (age and manual labor). If you are a smoker or use tobacco in any other form, your risk goes up even higher.