You should be fine just grab some home tests to put your mind at ease. The smoking back from Dec to March won't show up now, and because you only had a little bit last night it should be gone in a couple of days, I was a chronic smoker and passed a home urine test on day 22 of not smoking. Only thing to watch out for is different cutoff levels, I've heard some people can pass home test but fail the real thing.
If you're not passing them easily (i.e. with first void of the day) then make sure you don't excercise for 2 days before the test, and on the morning of the test drink plenty of fluids. (drinking lots of fluids for days/weeks before the test is a waste of time, just drink lots on the morning of the test)