Bad Gas?

I stopped at a Valero gas station I have never used. After getting gas I tried to start my car and it would start but after a few seconds in would stall. It did this a few times and right when I was about to give up it started and I was able to drive. I drove all the way to work, about 45 minutes, with no problems. I had one more instance when I got to work but I have been checking it every few hours with no further problems. Is this something I should worry about or maybe just a one time thing? I have put so much money in this car and I really don't wanna have to spend more.

Also to top everything off while pumping gas my gas door fell off. I can't catch a break.