North End took the lead at Deepdale through Darren Carter, but Paul Anderson levelled for Forest five minutes after half-time and Luke Chambers stabbed home from a Lewis McGugan corner in the 89th minute.
"I thought we started very well and in the first fifteen minutes we had a couple of opportunities to score," he said.
"We could have gone ahead and in fairness to Preston they came back into it well for the next twenty minutes.
"In the second half we were miles better. We created a lot of chances to score and I thought at the end of it we were value for money.
"I thought we could nick one and I'm delighted - the last thing we needed was another game."