[racket-dev] chaperones in 5.3.1?

I'm seeing the following error deep within Whalesong when I'm running
its test suite:


. . ../../../Library/Racket/planet/300/5.3.0.900/cache/dyoo/browser-evaluate.plt/1/0/browser-evaluate.rkt:145:0:
prop:chaperone-contract: expected a chaperone of
'#("#<path:/Users/dyoo/work/whalesong/tests/more-tests/js-binding.rkt>"
401 14 10 9), got
'#("#<path:/Users/dyoo/work/whalesong/tests/more-tests/js-binding.rkt>"
401 14 10 9)


I'm confused (as usual), because my browser-evaluate library shouldn't
be doing anything to chaperoned values.  The error makes it appear
that some value got incorrectly unwrapped somehow.  I'll try to trace
this down better, but has anyone else seen this before?