Could you share the reading score breakdowns too?
Broad Reading 2.9 132
Letter-Word Identification 3.2 142
Reading Fluency 3.3 145
Passage Comprehension 2.1 131
He has been reading chapter books since the age of 3 so we expected his reading scores higher overall. The passage comprehension took us by surprise but then so did his Applied Problems in math

I would love to know how he did on the comprehension. You know if he didn't do too well because he couldn't or because he was too tired or didn't pay attention or ...
I wouldn't recommend repeating this particular test yearly, as it is really not that indepth in any one area, but I do encourage "above level" achievement testing of some sort on a regular basis. Your son is young yet though for talent search versions. I wish we had 5 year scores on DS. Our first good data didn't come until he was 7.
Encore starts at 2nd grade, right? Is there something else?