quick torah question (Ha'azinu)

This isn't quite "help me do my homework", because I want to know more generally, but if anyone has insights that I can draw on this Shabbat, that'd be especially spiffy.

In Deut 32 (verse 15 and vicinity), Moshe is talking about God and Israel in the third person, talking about how "he" (Israel) did various things. He then switches to second person for a bit, directly addressing Israel, before going back to the third person. Specifically: "But Jeshurun waxed fat, and kicked--thou didst wax fat, thou didst grow thick, thou didst become gross--and he forsook God who made him, and contemned the Rock of his salvation." ("Jeshurun" is a reference to Israel.)

I'm looking for any significance in this switch noted by the commentaries. The chumashim I've consulted (Soncino and Eitz Chayim) are silent on this point (well, beyond noting that it happens).

Yom Kippur (short)

One sermon both interesting and frustrating (maybe more later). Organ broken, so even late (more-formal) services got piano instead (improvement in my opinion).

Went to early morning service. This left about 2.5 hours to occupy before afternoon service; sweet-talked the key-holder into letting me into library. Spent quality time with talmud investigating a question a friend emailed about on Wednesday (oven of Akhnai, Bava Metzia 59). On the way, studied some about ona'ah (causing people distress); this provided some material to think about before discussing sermon, so on-topic for Yom Kippur after all. Study time briefly interrupted when a congregant who had some sort of seizure was brought in to lie down; seems ok now, but paramedics took her away to be sure. (95 years old.)

Headache began around hour 20. Noticed dehydration around hour 22 (pretty good!), hunger around hour 23.5. Complete sentences departed around hour 24. :-)

Ne'ilah uplifting; Yizkor tedious. May re-evaluate the latter next year. (This is my problem, not the rabbis'.)