The visitors led twice courtesy of a Luciano Becchio brace but Grayson's side were pegged back by goals from Adam Boyd and Sweeney.
Leeds have only won once in eight games since beating Manchester United in the FA Cup last month and Grayson admitted: "It's very disappointing to concede in the manner we did but we have had it the other way around on many occasions, when we have scored late on.
"But it's a point away from home at a very difficult place. We started very well and limited Hartlepool to few chances in the first half and were in control and quite comfortable, looking like we would win it.
"But you always need that extra goal for comfort and we didn't get it. We allowed them to get back into it twice, it's disappointing to concede in the 90th minute and with the manner of it as well, we didn't feel it was a free-kick, but it's happened and we have to accept it.
"They were at home, with the crowd behind them and have some decent players. They had their moments, we could have been quite comfortable in the first half. I cannot knock the effort and commitment we showed, but it's disappointing we didn't win it."