Despite trailing 14-12 at half-time in difficult conditions at Scotstoun, with heavy rain and strong winds impacting play, Franco Smith's side turned things around after the break. A strong second-half performance saw the Warriors edge ahead and ultimately claim a 25-21 victory.
Samuel and his teammates now look ahead to a quarter-final clash against French side Toulon, who will travel to Scotstoun next weekend.
"Bulls certainly brought it, I'm just glad we dug it out in tough conditions," Samuel told BBC Scotland.
"There's a bit of rivalry ever since we went over there and won the URC. I think that's good for the sport.
"We're aiming high in both competitions, but we're just taking it match by match. Franco doesn't let us get too far ahead of ourselves. It's about Toulon next week, we're focused on that.
"We back our fitness all the time. We don't work so hard in pre-season to not dig out victories. We're one of the fittest teams in the competition and our second half performance shows that."