Breast milk while on Nexplanon?

Is it normal to have milk while on Nexplanon? I got Nexplanon on March 26 of this year, so I been having it for about four months and I noticed a warm waterfall sensation on my breast while washing dishes. I thought it was sweat (it’s hot in CA) and I sort of tried to wipe the “sweat” with a paper towel and that’s when I noticed it was in fact a couple of milk drops. Is this normal? Is this like a side effect caused by Nexplanon?

Background:

I have a 2.5 year old who I only breast fed a few weeks on and off from birth until 5 months due to my health issues and multiple surgeries. Then I became pregnant last year but I miscarried at 10 week (a year ago exactly)

And I got Nexplanon four months ago