The sound should be pronounced on prolonged turns in one direction or another, if it's wheel bearings.

It's not that hard to remove and inspect the bearings. I have photos I never posted that I'd like to put up somewhere into a walkthrough, but I'm missing a few steps that I didn't bother to photograph. I'd be happy to share them all the same.

If the castle nut is a bit loose, repacking and tightening it to spec (a little more than finger tight?) might fix it. At any rate, you should inspect them, but they'll get a lot worse (noisier at least) before they fail. That said, should you ignore them for 10,000 miles or so, they could seize up and lock one of your tires. That would be no fun. No rush, but don't ignore them.

Good luck!