Deception

A friend of mine has pointed out that I often conceal my true feelings for the sake of keeping peace between myself and those I am surrounded by. While this is obviously not done with any intention of malice, it turns out being slightly deceptive because it leads others to feel as if I agree with them when I really don't. Until my friend pointed this out, I never really thought much about it. I always just felt that I chose my battles very carefully, and didn't bother fighting when it wasn't something that I felt extremely strongly about. I do enjoy a good argument, and like debating, but only when I know it will be taken in the manner in which I intend, which is without personal insult, but to merely examine different ideas and ideologies. I don't like the thought that I am being deceptive, because I value honesty so much. But I also value not being confrontational just for the sake of picking a fight. I see too many people who build such incredible barriers between themselves and others over silly, petty disagreements. I would hate to give anyone else the opportunity to do that to me, or for me to do that to someone else. So is keeping the peace even when something bothers me deception? Should I air my annoyances more freely? If I feel someone is not going to actively listen and take anything from what I say, should I say it anyway? Is there a line between being deceptive and being peaceful that must be drawn, and apparently somewhere else than where I draw it?