Did you have detailed armor hits(shift-D) on? About the only way I could see it happen would be a weak point penetration.
Ingame the Tiger has weak points on at least on the front upper hull and front turret. That's only frontal Tiger kills I've ever seen by a 37mm, unless you count gun damage.
I've played around with a lone Tiger vs. Stuart hordes some since seeing simliar comments on this forum. On average it's taken around two dozen frontal hits to get the weak point kill but I've had it happen at as low as 2 and 5 hits. A few of the penetrations were no effect or 1 crew casualty so even a penetrating hit isn't a 100% kill. I wouldn't bank on gun damage either as one of my test Tigers took 5 gun hits for no effect.
In an even points battle, or even on attack, I don't think I'd bank on a few 37mm's taking out a Tiger.