Wait, what? Caltrain single-zone one-way with clipper is $3.75 [1], so that would mean your UberPool ride was less than $2. I've never seen that (after the promotions anyway).
The numbers might be close if you brought a second person with you, since you'd have to compare against two tickets vs UberPool + $1, but you say "a 1-way ticket".
[1] $3.20 with Clipper Card, but I'm erring on the side of making the numbers favorable to your claim. http://www.caltrain.com/Fares/farechart.html