Saints took the lead through Steven Davis's early header but Brighton levelled when Murray's header beat Forster at his near post - the Southampton stopper could only palm the ball into the side of the net as he tried to keep it out.
On Sky Sports, former Arsenal striker Thierry Henry and former Southampton and Newcastle manager Alan Pardew both felt Forster should have saved the header.
Pardew said: "When he (Pascal Gross) hangs the ball up, that's what Glenn loves. He just uses his neck muscles to head it but Fraser's a bit leaden-footed there.
"He should be across maybe another yard, a little bit livelier on his toes and he's been caught out.
"He's covering the first post when the cross comes from that side and if he comes across a bit more, he would have saved that but it's still a great header."
Henry added: "There was a slight deflection off Cedric and the ball went a slightly bit higher but they could have still defended it better.
"If Forster carries on going and expects the ball to go towards the first post, he can maybe save it. If the ball goes across the other side, well done Glenn Murray. But he stopped in the middle of the goal and then it's too difficult for him to get the ball because once you go on your heels, it's difficult."
Southampton fans were again unhappy with Forster's performance on Twitter, after the stopper was also criticised for the two goals he conceded in their 2-2 draw with Newcastle earlier this month.
Albion keeper Mathew Ryan was asked about the goal after the game and said: "My goalkeeper coach Ben Roberts came in and said our goal was a strange one but it took a little glance off the defender.
"If you're a goalkeeper and are setting yourself and think the ball is coming a bit closer, to be set and then have to change and try to push off can be that little split second that doesn't give you enough time to get more of a push to get there or not.
"It's hard to tell from where I was but it looked like he tried to react as quick as he could but fortunately for us it went in and he wasn't able to keep it out."