MAP testing isn't a placement test. Many kids have what is considered "summer slide" and the scores drop a bit. Its not that unusual. It would also depend on which version he was given. Did he take primary over the summer and 2-5 now (his score for the first test is at the ceiling of primary)

Here is the info on the test ceilings :
https://docs.google.com/document/pub?id=1nA_PlvjvwFTi5vMwRxlfmmVUJo63pfwn67ZAMHaV4oU

Here are the RIT charts with grade and percentile:

http://www.sowashco.org/files/department/rea/2015NormsReport_Reading.pdf