It could be, but it could also be something as simple as a loose wire scraping against the fan blade.
Try CAREFULLY inserting a wooden glue/Popsicle stick into the PSU and lightly
touch the center hub of the fan while it is making the noise. This will cause the speed of the fan to slow down just a little. If the problem is caused by the fan bearings or the fan blades hitting something, the sound of the noise will change in step with the rotation speed of the blades.
If the sound remains the same when the fan speed is reduced then the noise could be coming for an induction coil (called coil whine) or from loose plates in a transformer (typically causes a buzz noise). If a coil or transformer, the PSU may last for years, or days - no way of telling.
Anything that plugs into the wall can KILL! With a computer, that's the power supply. I do not recommend unqualified non-technicians opening up a PSU. If you cannot see an offending wire in the way of the blades you can carefully push away, it is best to just save your pennies and buy a new PSU - then use this one as an emergency spare.
For new PSUs, I recommend getting at least an 80 PLUS Bronze certified PSU and one from a reliable maker. I like EVGA and Seasonic. If you avoid the budget lines from Corsair and Antec, those are good too.