its a tough call...I had 45 min nappers from the beginning and they survived on their 45 mins naps till 4 mths....so I would say, yes, wake him as otherwise, you're going to get less feeds in in daytime and this may mean more NFs.
You *COULD* allow him sleep and hope that he'll cluster and tank up in the evening,.....but I wouldn't be that brave!
s x