Something in your stock is mostly likely rubbing against this mechanism. It may need a bit more inletting around the new trigger mechanism.
I had the same issue you're having (sorry, can't remember exactly how I solved it) and a safety issue with my RB trig.
Don't want to bad mouth them, but had trouble with my safety after installed on Rem 700 last year. Sent it back to the factory and they sent it back to me and said it was fine. Wrong...it was not fine--far from it. Fortunately, Midway was gracious enough to take it back. It was exchanged for a Jewell which has worked flawlessly once installed and it's all SS construction so there's less rust issues to worry about.
There is at least one trusted 'smith that helps out on this site quite a bit that wrote sometime last fall, I believe, that he was only going to be reccomending Jewell trigs to clients and not RB anymore. After getting the Jewell and seeing the difference in construction, etc., I should have gotten one years ago. Just my experience. I'm sure others may have had the opposite.