Clicking?

After two weeks of yoga without consequence, this morning I went to the gym to do the exercises Chip gave me. When I finished the series of exercises, I decided to see whether I had gained strength (although I knew I had), so I went back to some of the exercises I used to do with the physical therapist. When I got to the marching, I noticed that when I raised my (operated) leg, there was a painless catch or click that I could feel, rather than hear, and I wonder if that's normal.
It's almost as if the joint is catching up somewhere, and maybe it's on a muscle, tendon, or ligament that surrounds it.

I'm gonna ask the experts. Better safe than sorry.