Section 7, Second Paragraph:

  “A node MUST NOT send more that one Source Prefix sub-TLV in a TLV, and a node
   receiving more than one Source Prefix sub-TLV in a single TLV SHOULD
   ignore this TLV.  It MAY ignore the whole packet.”

1. “That” -> “Than”
2. This paragraph implies that a node might accept the TLV with more than one Source Prefix sub-TLV, but it does not state when a node can do that.
You might want to elaborate on the conditions that a node is allowed to do that.

Otherwise, the security considerations section seems reasonable and addresses the issues that might arise because of the added flexibility of the source prefix.

Regards,
 Rifaat