I noticed last night when I was getting on the freeway that a little smoke was coming out the exhaust the whole time I was getting up to freeway speed. I really noticed it becasue someone was behind me (this was a night) and I saw it their lights. Is this a usual thing? I was under the impression that there shouldn't be any smoke. I have about 2300 miles on it and changed the oil at 2000 with delvac 1300.