Let's look at this logically.
You don't eat the bullet
When dressing ducks you remove the shot
So how can you get lead poisoning
I've been been a hunter for over 50 years and I'm still ok.
Sometimes the reticule is sticky try winding it vigorously back and forward on both elevation and windage this worked for me, it drove me nuts when it happening to me,, hope this works for you.