Town looked set to suffer their first defeat in seven matches when Bira Dembele's first-half header gave Stevenage the lead.
"It was a game where we took control of the first half and really got on the front foot and played some intelligent football considering the conditions, which were very difficult," said Westley.
"We got ourselves ahead through a well worked set-play, which was nice, and at half-time there looked like there would only be one winner.
"But you always knew that a home side that hadn't travelled at the weekend or didn't have to travel here might have a little burst of energy at some stage and sure enough we looked like a travelled side in the second half."
Day had little to do in the Stevenage goal but despite saving the spot-kick from Tubbs, Westley had little sympathy for the goalkeeper after conceding late on.
He added: "I don't feel sorry for a goalkeeper that lets a goal in because his job is to keep a clean sheet. If you start feeling sorry for someone who hasn't done his job than you're on the road to ruin.
"It looked as if our goal was going to live a charmed life and we were going to get away with it but in the end you'd have to say they deserved the point and probably could've got more."
- Sports & Recreation
- Matt Tubbs