I think I may have. I did a couple of outcalls to a guy and I think he may have worked in a different department at a company I used to work in.
Strangely enough, I used to work for a civvy company which had offices in Brighton and two other much bigger cities. I lived in Brighton and worked from my flat there both during and after leaving the civvy company. I never worried about bumping into a colleague. (Big company, well over 1000 employees at every site.) But touring the other two cities that had offices, I was really anxious about getting an ex colleague turn up. Totally illogical considering I probably knew 100 people by site in my "home" office but only a dozen or so in the others.