What does it say on your tickets?
I sold some a few years back (on Ebay) and it did actually state on the ticket that they were not to be resold. I made the mistake of giving the details of row/seat number on Ebay and soon received an email from the promoters advising that the tickets were not allowed for resale and I should remove them immediately. Unfortunately by that time they had already sold.
I explained the problem to the buyer but they insisted that they wanted them anyway and I never heard anything else so I assume that they weren't refused admission or anything.
Like you, I wasn't selling to make any profit, I genuinely couldn't attend.