Hi everyone, I'm new on this forum

I have a 1996 Civic LX with 58,000 miles on it. This morning I went through the required Memphis emissions test and vehicle inspection, and got a print out of the carbon monoxide and hydrocarbons detected in the emission test. In the past when i've taken this car through, both readings have been at or very close to 0.00. This time however for the hydrocarbons, the car put out 35.07 PPM, and for carbon monoxide 0.03. I'm not very concerned about the CO, but I am curious about the hydrocarbon output.
When I was in line and when it was being inspected, the A/C and other accessories were all off. The car was plenty warmed up before going through.
The only things that I can think of that have been changed (engine wise) since last year are the gasoline grade (using 89 octane instead of 87), and I had a tune up done back in like October '06. Also, oil is changed about every 3 or so months (I don't drive the car enough to go 3,000 miles in between oil changes.)
The car passed inspection fine, but i'm curious as to what made the hydrocarbon count go up. If there is a problem, I don't want it to snowball into a larger problem that would cause issues or prevent passing inspection next year.

Any help or ideas would be greatly appreciated!

P.S.-The engine is a 1.6 liter non-VTEC (sorry I don't know the model number off the top of my head)
Thanks,

Aaron