The visitors opened the scoring through John Sutton and Andrew Driver gave them a 2-1 half-time advantage after Rowan Vine had levelled the scores, but Steve MacLean equalised for Saints after the break.
"We had a chance to make it 3-1," McGlynn said.
"It was a great knockdown by John Sutton and Gordon Smith is there and I think at the very least the Hearts support thought that was going to hit the back of the net, he just didn't catch it right.
"If we'd gotten the two-goal cushion then it might have been enough.
"It was a very well earned, hard earned, point for us. St Johnstone looked dangerous and we've Jamie MacDonald to thank for some really good saves.
"We've not had a great record here, so a point in Perth is fair enough."