Lennon, who managed Brown, now 31, in his four years as Celtic boss, says the midfielder's decision would boost Gordon Strachan's Scotland squad.
"It is not a surprise because I thought he retired too early," said Lennon.
"Sometimes you can make these decisions and then think you have still got plenty to offer."
Brown's return to the fold means that on Wednesday he is almost certain to be included in Strachan's squad for the World Cup qualifier against England at Wembley on 11 November.
Lennon told BBC Scotland: "I think last season his injuries took a toll on him and we didn't see the best of him but certainly this season he is looking far more like himself again and playing very well, which will be an asset to Scotland.
"I think his presence around the dressing room and training ground and certainly on the pitch will be felt if he is not there.
"He is only 31 and there is plenty more to come from him. I thought his decision was premature anyway."
Lennon does not envisage any issues with Brown returning to the squad for a game he believes Scotland can win.
"I don't know how it would affect the dynamic of the group but certainly I think it would pep it up," he added.
"It was a poor performance and result in Slovakia and it might just give them the wee jag they need, having a player of that quality back.
"The England game is one I think they can win. It will be a British style of game and there won't be anything the Scottish players will be surprised about."
Scotland assistant manager Mark McGhee, meanwhile, looked forward to the team benefiting from Brown's leadership, saying "by example and his voice and influence, (he) makes other people better".
McGhee added: "Scott Brown is someone who I would imagine, when England are looking at our squad and our team, would prefer him not to be playing.
"He looks as if he has coped better with combining the European and league campaigns. He feels good about himself and he can do both at this stage.
"I would imagine he has been revitalised by Brendan (Rodgers, the Celtic manager). I think the manager has given him a new lease of life.
"He would have made his [original] decision in an honest way. But now he has looked at it and decided it was clearly the wrong decision.
"If the other players feel that Scott Brown gives us a better chance of winning the game, they will be delighted to have him back."
Hibernian's Neil Lennon believes Scott Brown retired too soon from Scotland duty and still has plenty to offer now he has decided to return.