Interesting about the lead having that effect, Kate. I always have almost always relaxed the lead when my dogs greets another and all goes well, to the extent that people have commented on how well she is (he was) on lead.
Apologies though - I do need to work on my written language on MN - I frequently use shorthand and not give the full story or my full thinking. On the occasion I am thinking of, my dog was on-lead (aged around 9 at best guess and seemingly very friendly) and other dog (16 months) was off-lead in her garden, so separated but happily sniffing through a gate (I was talking to her owner). The young dog did the "snarl" expression which startled me so I pulled mine back, at which point she went in to full growl, almost as though it had been there, waiting behind the curtains, IYSWIM.
I think I am just doubting her, which is unjust to her as she seems so friendly, so I would love to know what I am doing wrong. The other day I introduced her to an American Bulldog whose owners, to their credit, were trying to socialise him. I saw his tail raise high in the air and his ears became on full alert after about 10 seconds of sniffing, although she was usual "low slung approach" and remained so but I became worried looking at what I had interpreted of his signals.. you know that silent, slow moving thing.. so encouraged her away with a quick tug on the lead and she went into full growl mode and reared up to him... and yet quick to want to get away after what I saw as "telling him off". She does seem rather maternal and fabulous with puppies, which is unusual in many older dogs I thought.
Sorry, I seem to be monopolising this thread. Sorry Weejie.