I noticed such an effect long, long ago. To do historical synthesis you have keep large packages of historical "fact" in mind while you attempt to correlate events and persons. Otherwise, you'd be obliged to reside in a library of open books, with the books kept open changing on a daily basis. I have (or used to have) almost photographic recall--i could take a volume in the pre-internet days, and open it to within a few pages of the place at which i had read something, and recall if it was on the left-hand page or the right-hand page, near the top, middle or bottom of that page. I could "see" the relevant passage in my head--it's still a good idea to check your accuracy, of course.
But i also found that if i had heard something, rather than read it, the memory became less accurate over time. The internet world is useful in that if one is careful, on can check one's facts before inserting one's foot in one's mouth. The huge caveat, though, is recognizing the enormous amount of unreliable information online. I use sources such as Wikipedia to check dates and the spellings of place names or personal names. The amount of just plain wrong "facts" there, some of them hilarious and even self-contradictory is impressive.
