It's not too good to be true. It's just Jon proving us wrong one more time. Here's something I could imagine JBJ having thought about recently regarding his voice (not really, but we can always imagine, right?):

"F***, I'm still sounding bad. I've done everything I can and yet I haven't really improved. *sigh* F*** it, I'll try. Now, how did I sing all those high notes back in the day? OOOOONCE again. OOOOOOOONCE again! Shit, I'm almost there. Big John, could you come up here and kick me in the balls - maybe it would help? One, two, three... OOOOOOOOOOOOOOOOOOOOOOOOOOOOONCE AGAAAAAAAAAAAAAIN! Nailed it. Thanks, bud! Now, let's see if I can still sing Let's Make It Baby..."