Really small rash that doesn't fade but feel absolutely fine

[Countingdownthedays2019]

Hi, I have a very very small rash/bruise like rash that has appeared today, it is very small and doesn't appear to be spreading etc.
I had an ecg Sunday night at A and E, and they mentioned that my skin was reacting to their ecg pads, coukd the rash type thing be from that?
I feel completely well.
Would you worry about this or keep an eye on it? Obviously if I felt unwell i would get it looked at, but with me being well and it being very small I'm wondering if it's a waste of time.
Oh and the ECGs showed tachycardia and poor r wave progression, but all further tests when they took me to hospital were fine and I was sent home and told to make an appointment with the doctor for further investigation.
Added a pic to show how small this rash/bruise type thing is.

[Countingdownthedays2019]

.