Athlon BTR GEN2 parallax

Has anyone had this problem? I get the parallax set @ 50 yds. and then shoot and it needs to be set, just a little, to be set again. Reset it, shoot, adjust again. Do I send it in or ia there an adjustment that I can make to keep it set. Can't tell if the knob is moving because it only takes a very little move to get it reset. Has only been used about 100 times and 90 of that was trying to get it set.
 
Update -- Sent it last Friday by UPS. They got it Tuesday @ 10am. By 4pm Tuesday , same day, I had an email stating they would check it out and let me know about it.

Today at 3pm I got an email that they were replacing it and the new one is on the way with the tracking # included.

Thats what I call GREAT service.

Thank you Athlon.

Don

Great customer service! One of the reasons I purchased an Athlon scope and binos.