I had a little drianage from one spot on my neck incision as well after rad. When I was in the hospital post-rad with the mysterious fever, they actually did another CAT scan on my mouth and neck to be sure I wasn't feverish from some sort of abcess and the guy reading the CAT scan wrote that there was a TINY "abscess" underneath this one piece of my scar--my medical oncologist said he didn't think somehting that small could even be called an abcess--they never attempted any surgery on it (it was only one week post rad, my entire neck was still burned, and I was so sick otherwise, surgery on that tissue would have been a really bad thing unless it was absolutely necessary)but I did get a little drainage later on.

If you get much additional swelling there, or a distinct red spot, I would think you might want to have it looked at, though, just to be sure it isn't an abscess that really does need some sort of other treatment.