There was another element to the grin, though, as Prince could look back with satisfaction over his decisions leading up to Saturday's mile.
Prince, who is based at Wingatui, was left with two options for the O'Reilly gelding's lead-up race after things went awry at Timaru in December when the 5yr-old held his breath during the running.
Prince opted to send Ric O'Shea to Gore instead of a race at Riccarton, and due to the horse's high rating in a rating 85 benchmark affair, he carried 63.5kg but ran on well to finish second.
''A lot of people bagged me for 63.5kg, but we tried some gear changes [a tongue tie and a shadow roll] on him, and it worked at Gore,'' Prince said.
Prince won the group three mile in 2004 with Volronamo, but he is now having to reassess his rankings of horses he's trained after the ''very satisfying'' win.
''This horse is really good,'' he said.
''He's getting towards the best horse I've trained.''
Prince has also won listed races with Chaparella, Volronamo and Whyte Haze, while Tooth is his other group 3 winner after claiming the 2000 Stewards Stakes.
The win provided Kylie Williams with a race-to-race double after her success in the Dunedin Gold Cup and also gave Palmerston owner/breeder Andy Denham some black-type success for his mare Fellowship.
The Success Express mare - who placed at group three level in Melbourne during her race career - had three of her foals racing at Wingatui on Saturday, with Ric O'Shea joined by Red Bull, who finished fifth in a special conditions 1400m maiden, and High Jinks, who was 10th in a rating 65 2070m event.
''This has really set her up for other siblings,'' Denham said.
Denham has always chosen top-quality sires, with High Jinks being by High Chaparral, and Ric O'Shea appears to have inherited the best traits from O'Reilly. Patience has certainly paid off for Denham, who farms sheep and cattle at Stoneburn, just west of Palmerston.
''I've been waiting for something like this,'' he said.