The 23-year-old was forced to miss the town's school concert on Wednesday evening to partner Fill the Power at Sedgefield.
But he still brought plenty of cheer to proceedings as his victory in two-miles four-furlong chase was announced to the packed audience in the Volunteer Hall.
And it was only when Braw Lass Nicola Mackay called him later in the evening that he realised he'd reached the century milestone.
Ryan told the Border Telegraph: "I knew I was coming towards my hundredth winner when I won my 98th but it had slipped my mind again.
"I didn't realise I'd ridden my hundredth winner until I got a call from Nicola later on. It's obviously a great milestone to reach."
Ryan, who rides out of the Sue Smith yard in Yorkshire, relinquished his jump jockey's licence briefly last year. But his return to the saddle has been met with plenty of success.
Ryan added: "The trainer I rode for was banned and I wasn't sure what I was going to do last year. I'm pleased I've come back to riding as I'm really enjoying it."