I remember after my very first punt, I did feel a little pang of something (jealousy maybe?) when feedback from subsequent clients appeared. But I knew it was inappropriate and irrational (even at the time, I thought "what the fuck is this?"), and it very quickly ceased to bother me after that.
Nowadays, if anything, I have the opposite reaction. My current regular was a zero-feedback newbie when I spotted her: a couple of guys got in and gave her feedback before I got to her, but I was the first UKP member to report back, and I gave her a positive review. Since then, even though she's "my girl" (sort of), I feel a little glow of pleasure when more feedback arrives for her. After just a few months, her rating is now in the 40's and rising rapidly, she's doing well and I wish her all the best. I might be partly responsible for her success, and I feel good about that (no, I'm not her pimp... I wish!)