"I think in the early stages of any cup competition people are always a little bit disinterested and that's maybe been the case with this game," said Gray.
"Hopefully we can get a few more here for whoever we play in the next round.
"It would be nice to get a home draw and get a full house here at Sixfields. We'll gladly play anyone at home."
And the manager added: "It was an ideal night for defenders and both our centre-halves played really well. They did the nitty gritty stuff really well."
Originally the crowd was announced at 1735, a record low but the number has been ammended.
Club customer service manager Paula Kane explaining: "In calculating the attendance figure for Tuesday's Carling Cup match there was a noticeable difference in the three separate counting systems which are used to determine the attendance, namely the computerised count, manual count and box office reconciliation system.
"We anticipated, at the time, that the error was with the computerised systems and made the decision to announce the attendance figure of 1,735 which was the lowest figure available, as we felt it was imperative not to overstate the attendance when announcing the figure in time for the second half of the match.
"On Wednesday morning we had the opportunity to reappraise all of the information and investigate where the discrepancies were, and can confirm that the actual official attendance was 2,382, which included 228 visiting Millwall supporters."