Scary moment on ride yesterday

[deluz]

I am just starting to get into longer and hillier rides after a year off due to health problems. Yesterday I did a moderately hilly ride (1900 ft) that I have done probably a hundred times before. One section of the ride has a long twisty descent through a canyon that can get pretty windy. It is a narrow road with high speed car traffic. Yesterday the wind was gusting and part way down the front wheel started oscillating back and forth and I had to put on the brakes.
I was riding my new Tarmac SL8 with 40mm BTLOS wheels. On previous rides I had noticed the wheels catching the wind but nothing serious like this.
The rims are GX40 22mm internal width and thought this shape rim is supposed to be less subject to catching the wind.
I am not wanting to change wheels and decided not to ride this road anymore since I am 67 and wanting to have less risk as a crash could be disaster.