I didn't wear my watch to bed for the first time in months and now my RHR has spiked. Would that explain it, or could this be a predictor of illness?

25f, been wearing my Garmin Forerunner 645 for several months now, always overnight.

My average resting heart usually hovers around 50. Today it's spiked to 65 with no warning. The only variable I can think of is that I didn't wear it to sleep last night, so the only data it has is from after I woke up, and the first 4 hours of my work day. I work a desk job, so I am sitting, but that's definitely higher than while sleeping. I just don't know how RHR is calculated, I saw someone say that since sleeping heart rate is so much lower it isn't counted to your RHR anyways?

I don't know if I should be worried by this spike. (I read a couple threads that a spike in RHR can predict sickness 48 hours before you have any symptoms, and got pretty nervous about that). Would not wearing it to sleep skew the data, or is something else at play here?