Yes: that could be a reason...
But please: have a look at this link.
We all know that transcribers working for publishing companies worked with reel-to-reel tapes those days to do their work. A paragraph from the link provided says:"...When the Beatles signed on with Capitol in late 1963, the reel to reel tape was the only tape alternative to vinyl. Professional recordings were made on reel tapes (as some still are today). These were reproduced at one half or one fourth of the recorded speed for the public..."
A professional transcriber from those days, who worked for some publishing companies in the USA, told me that:"...When I was doing takedowns, transcriptions, arrangements, etc., one problem that occasionally surfaced when given a tape (usually an open reel) was, 'what speed should this be played at?'..."
So..., wouldn't have faced with the same question the transcribers working for Northern Songs by those days??
And..., did The Beatles by those times (=for example, for the sessions dated February 1964) tune their guitars in A=440 accurately??
Doubtlessly, Northern Songs had their own transcribers back in the sixties to do the work. if that song (=as many others) was published in E flat instead of the original E, was due to one of the following reasons:
1) The reel-to-reel tape was played at slower speed
2) The Beatles didn't tune their guitars in A=440, but ca. 415
3) Dick James didn't want to publish a song with four sharps (=for commercial reasons...)
It would be very interesting to find who were the transcribers working for Northern Songs by those days...