I was instructed by the guru at the my LHS that a Med gap filling CA (that he provided to me) would be more than sufficient in connecting my wings on my Sig Kadet LT-40. I followed his advice, should I be worried??
I think you're saying that you did fiberglass the wing halves together, but you used medium CA instead of epoxy.
There is no point worrying. Just make a test joint and find out. Now is a better time than when you're 100 feet in the air. Take two pieces of balsa, butt them together. Glass them together with medium CA exactly as you did for your model. When it's dry, really try to tear it apart (be ruthless, your plane is at stake, not your reputation). If you can get the fiberglass off the balsa, then yes, you should worry. If all you can get apart is little tiny bits of balsa, then go fly without worry, and for sure don't worry about a bunch of folks on the forums!
I can tell you that if you do this test with epoxy, the fiberglass, epoxy and wood will join into an incredibly tough but flexible unit that is all but indestructable. If your CA joint is not close to this, I'd use epoxy next time.