I have had a similar experience among fellow practitioners. A few of my Buddhist friends were talking about some peoples practice being a bit fanatical and they both looked at me with a pregnant glance which I was really surprised by. Like you say I just feel motivated to practice precepts and do what I can to further the Dhamma practice of myself and others. I get the impression that if you give in wholeheartedly to your Dhamma motivation it can cause some disaffection with those who might feel it challenges them. I really dont feel fanatical but maybe that is how I am seen by others. I must admit that this is difficult for me. I am blown by the 8 winds and trying to maintain awareness of it.
"Beautifully taught is the Lord's Dhamma, immediately apparent, timeless, of the nature of a personal invitation, progressive, to be attained by the wise, each for himself." Anguttara Nikaya V.332