But okay, past tense slips through from time to time.
And you do note:
I'd have to look at Yoda's speeches in their context to be sure, but I suspect that one difference, in terms of discourse structure, is that Yoda is much more willing to front new information, while most of the rest of us front only old information, if we front anything at all....which indicates that he would prefer present tenses more than the average jedi.