Hasn't gone #2 in 5 days!

Alright, my husband just broke down and did a flush last Sunday/Monday. He did get some stones out, and that was pretty cool to him. LOL :) However, he hasn't gone #2 since the flush. We're here on Friday and I'm really starting to wonder why. I have done many of these flushes and have never gotten constipated. He's also very regular, usually, in his #2 habits...

Advice anyone?