Gemmell hit the headlines by criticising the Ibrox club's manager and players on the social networking site at the weekend.
But Foster, who started his first game in two months at Ochilview, reckoned the comments had inspired the Gers players to a 2-0 win.
He said: "I don't think there was anything horrible in it. It was maybe spur of the moment. We've all done that.
"That's the beauty of Twitter. You can say what you want from behind a computer screen.
"But the boys were talking about it before the game."
Stenhousemuir striker Gemmell had hit out at the Rangers players on Twitter for earning "£5000 a week" and being unable to play three games away from home in six days.
But Foster laughed: "I wish he was my agent!"
The defender added: "That's part and parcel of the game.
"I can't see that comment doing anything other than annoy us and giving us an extra incentive to win the game.
"He maybe thought it might give them the edge. We were professional and got the job done.
"I didn't say anything when he came on. He's 6ft 4in so I kept myself to myself."
Gemmell is a lifelong Rangers supporter and an Ibrox season ticket holder. Foster said: "He might have to wear a scarf over his face when he comes back to Ibrox!"