Wade, Dirk, and Kobe all got one in recent years. And while I'm not sure Duncan made it known, I believe pretty much everyone believed he was going to retire as well and he sort of got one as well.
Happens in baseball all of the time, including recently Chipper, Papi, Jeter, Rivera, Cal, Gwynn, Griffey, and Ichiro. Aaron, Berra, and of course Gehrig all got one as well.
While a bit different in the NFL because they play so few games, I think everyone knew Brady was done as well and he was sort of honored for that.
It really isn't a big deal if the player actually knows. I think most of the time they just don't know till the final season ends.