No, never an erection. Takes a helluva lot more than that!! It is very awkward, for sure. I'm always nervous about it and dread it. Last time it happened, I had a urinary tract infection (I didn't know that til the doc told me; my right nut swelled up about 4 times normal size and hurt like hell). That time, he barely touched it, and I nearly punched him. Does that hurt? What the hell do YOU think? But yeah, for physicals and stuff, it really is weird. Not my favorite thing to do, for sure.
Oh, by the way, if that nut-swelling thing ever happens to you, drink a lot of cranberry juice, no alcohol, and lots of water. If it doesn't clear up in a week, see a doctor. Just in case.