Comment 2 for bug 1297173

The object detail headers returned by Rados gateway to swiftclient does not contain the 'x-timestamp' header that Horizon looks for.
'x-timestamp' is returned in the case of a Swift backend.

A closer look into the response headers:
{'content-length': '154', 'x-object-meta-mtime': '1394533200.312213', 'accept-ranges': 'bytes', 'server': 'Apache/2.2.22 (Ubuntu)', 'last-modified': 'Mon, 24 Mar 2014 12:03:59 GMT', 'etag': '7cb550ed2aa02c83247878e3df5fbcc5', 'date': 'Mon, 24 Mar 2014 14:01:08 GMT', 'content-type': 'binary/octet-stream'}

Ceph sets the last modified time in "x-object-meta-mtime", which, IMO, is the parameter that needs to be checked.