This is not uncommon. Among the things it could be:
1) a small piece of airborne debris (I’ve had lint and spider web fragments) may have found its way between a stator or rib and the membrane. This can create a current leakage path between the two. Charge (and static voltage) can build up at that spot till it sparks across (the tic sound). The cycle repeats until the debris is sufficiently eroded away by the process.
2) a micro path through the stator insulation can develop (rare) with similar results. Sometimes this too resolves on its own.
I doubt it’s the backplate. Backplate issues are almost always heard on the entire panel, not just one spot. If you blow (just not super hard) on the spot where you hear the noise you will likely temporarily alter it. If so then it’s essentially 100% that spot on the panel.
Good luck and let us know.