Hi,
as Dana says .. it is a little current. Did you calculate this current? If not, do so!
Then compare this current to the maximum allowed ESD diode current (may be named differently) of your microcontroller. You need to read it´s datatsheet.
We did not get a link to it ... for a detailed discussion, nor do we hav any information about the microcontroller.
Then you say "Before" .. what does this mean? What range of time do you speak about?
What range is VIN?
So we don´t know: timing, VIN range, microcontroller type, expected accuracy, other requirements (example: max additional current drawn from VIN and 3V3)... or whatever is important ...
**
Side information:
I expect the measurement rather inaccurate because of
* high impedance resistive divider (read microcontroller datasheet)
* I guess you "compare" against an inaccurate VCC
Klaus