Loud Hum on 02 Malibu

My 2002 Malibu is experiencing a loud engine hum at above about 20 mph. It gets bad around 40 and then gets better. The car runs fine otherwise...pretty smoothly and I notice no other problems. Back in January I had to have the solenoid repaired. The check engine light came on briefly but cleared itself after a March oil change.

The car seems to be fine with 49,000 miles on it. Should I be worried?

The hub bearings on these cars are JUNK. I'd bet it's where your hum is coming from.

The hub bearings on these cars are JUNK. I'd bet it's where your hum is coming from.

Agreed, probably the hub bearings. Does anyone know if there are aftermarket hub bearings available that are better then the oem ones?