I have had a Fitbit heart tracker for several months. Typically, it reports my resting heart rate around 60 bpm, with a standard deviation of 1-2 bpm. A month ago, I got some kind of strange flu/cold hybrid, and starting about the same time I noticed symptoms (maybe a day before), my resting heart rate rose to 67, again with a standard deviation of 1-2 bpm. My primary symptoms lasted for 3-5 days, but I had minor symptoms that lasted for two weeks afterward. After the secondary symptoms went away, my resting heart rate dropped back to 61–62.
Is it normal for a cold or flu to noticeably elevate a person’s resting heart rate, and if so, why/how?