Ruddy had been established as the No.1 at Carrow Road before suffering a thigh injury which required surgery and ruled him out for three months.
Bunn has taken the opportunity to impress and was again in fine form in Saturday's goalless draw against Southampton, but Ruddy's comeback will present manager Chris Hughton with a selection dilemma.
"The main thing is the clean sheet. John's fit in a couple of weeks so I'll just keep working hard," said Bunn.
"I was a bit disappointed letting in four against Man Utd but I've been delighted with my form."
Bunn was disappointed that Norwich were unable to snatch a late win over Southampton after Grant Holt's stoppage-time penalty was saved by Artur Boruc, but he still believes there were positives to take from the game.
"They seemed to be coming at us quite a bit in the second half but at the end of the day I'm pleased to keep a clean sheet, and hopefully I can keep another one in the next game," he said in the Pink'un.
"It was disappointing from us today; we weren't really at our best. If we'd have scored at the end there, I don't think it would have been a fair result. I think 1-1 would have probably been a fair result.
"We had a great chance to get the three points, but it wasn't to be so we'll take the one.
"We were not at our best but we could have nicked it at the end and that would've sent us 10th in the league, so that is how tight it is."