This warning is perfectly fine and expected.
With XPAGEON the assembler automatically puts an XPAGE instruction at the end of
a 256 byte page to move the last assembly code from the current page to the
next page. (If the last instruction is a 2 byte instruction, a NOP and XPAGE are
inserted). However with XPAGEOFFenabled, this doesn't occur and it is possible a two byte instruction may be split between pages causing problems.
Please see the CYASM assembler guide, Section 3.1 Address Space, and the XPAGEON, XPAGEOFF instruction for more details.
However in this design it is just a warning and doesn't cause any problems. In this design this warning always occurs for the EnCoRe build.