What is the likelyhood....

That after 31 days of not smoking thc metabolites will show up in a confirmation test? I use to be a heavy smoker but I quit in Dec. 2012 and was clean for 6 months. Then i had two hits about a month ago. I tested several days ago and had a false positive for another substance (not thc) so I told them to send it to a lab for confirmation. The original drug test was a 10 panel screening and I hear they are prone to errors.

I'm 6'5", I weigh roughly 130lbs, and have high metabolism. I've had to ride the bike for about 13 miles almost every day for a while so I get a good amount of excercise.

So if they are looking for something else, would they be able to look at everything in my urine? What's the likelyhood it'll say I've comeback with THC? The false positive would be attributed to one of my actually perscribed medications I take for epilepsy.

Usually they just test for the suspect substance and leave the rest alone.
With only 2 hits over the last month and you're high metabolism you should be fine.