I thought the Yoda training issue was cleared up nicely by the scene in AOTC where we see Yoda training younglings, implying that Yoda basically teaches everyone before they get their own dedicated mentor. I wouldnt expect Obi Wan to say "You must go to Yoda, the jedi master who instructed me...well, actually to be specific my master was this guy named Qui Gon Jinn and he got killed by Darth Maul. Oh yeah, Darth Maul was the Sith apprentice before Darth Tyrannus and Darth Vader. But nevermind all that. Yoda is a guy who taught me before Qui Gon became my master, as i was saying. So anyway go to Yoda...Luke? Still alive?"

Yoda instructed Obi Wan. We dont see Obi Wan as Yoda's padawan but he does indeed instruct him, as he claims in ESB. Not a big deal. I think the OT has much bigger holes than this. "Certain point of view" ring a bell? At least we thankfully never had one that bad in the PT.