WTF happened here?
34 yo anon, so my max heart rate is around ~180 bpm. To reach it I have to exert a really high effort like continued hill climbing or long sprints, but even then it usually stays in the 165-175 range.

Today I went for a sprint training session. Everything went normally until one of the last repetitions, where I noticed my watch was showing a HR of 199. I didn't feel anything out of the usual so I continued with training, including the cool down run, but my heart rate stayed unusually high even at that slow pace. It also took a while to get into a "normal" HR, staying around 130-140 bpm for an hour or so after finishing.

Later I found that I might had too much caffeine in my breakfast (around 460mg). Could that explain that inhumanly high heart rate?