Well, is this the only print whatsoever that shows it? Or is this some kind of consistent thing you can duplicate?

If it's only at the edges and the rest of the print is fine, I'd double-check the enlarger lens to make sure there is nothing wrong, optically - but it doesn't immediately seem the source to me. I've definitely seen this kind of "blooming" before and it's never immediately bothered me, but usually my edges are fairly clean.