Paint coming when I snap back the trigger!



Hi guys
I was away for a few month for family reason! But I'm back and start painting again but I just noticed when I snap back the trigger basically is spiting one darker patch on the paper in a last second. I have one Iwata neo gun I tested high and low psi different mix most of the time do this when I do some slower move.
I forget the technic or I have something with the gun?
Any ideas guys?
Thank you
Could be a dirty nozzle, or I sometimes get that when my paints aren't thinned enough, or sometimes tip dry will do that to me as well.
Also, don't allow the trigger to snap back. You can damage your nozzle and needle pretty quick that way.