Me, myself and I in interpreting

As an interpreter you interpret in the first person. Anyone even remotely acquainted to interpreting will tell you that. It’s one of the first articles in any interpreting guidelines. The reason for using the first person when you interpret is that you are the voice of the person you interpret for. If you use the third person instead, for instance: “He says that he does not remember that day”, you take away the voice of that person and by taking away the voice you also take away some of his or her credibility.
Now, this is something I have never had any problems with. No problem to interpret in the first person, and I have interpreted in many different context both very formal (such as ministerial meetings) and very informal (such as house call with a midwife). The first person singular was never a problem, until I started interpreting for my friends. I live in a French speaking area and have friends who do not speak French, so from time to time I interpret for my friends, at the doctors, at the garage and so forth. And for the first time in my career it’s hard to use the first person. Instinctively, it seems, I use “my friend needs to…”, “Madame says that…”. As soon as I realize what I’m doing I stop of course, but then, unconsciously, I slip back to third person again.
I have no idea why this happen, I would guess that for the first time I interpret for people I know very well, and because of that it feels strange to be their voice. It does not bother me with complete strangers, but apparently it bothers me with people I know.