I'd have gone straight to the glucogel after that number, too! No harm in doing that, at all. But any time you get a number that seems out of place (either high or low), it's a good idea to re-test because sometimes the strip is bad, there's an air bubble, etc.
If she's still low when you re-test, here's the procedure:
Feed/give glucogel (glucogel if below 2.0-2.5, a tsp or so of high-carb food if between 2.0 and 3.0), test again in 15-20mins. Keep going until you see numbers above 3.0-- in that case, don't feed, but keep testing to see if she can hold on her own.
How long ago did you shoot? What dose of Caninsulin is she on?