#<Chef::Node::Attribute:0xxxxx) sometimes returned instead of attribute value

Sometimes, when requesting a value for an attribute, I get back a Chef::Node::Attribute instead of the value I expect. I've caught it in a debug session. For some reason, calling #to_hash on the parent object causes the issue to flatten out.

For example:

(rdb:1) node[:lt_demo][:app_env].class
Chef::Node::Attribute
(rdb:1) node[:lt_demo][:app_env].keys
NoMethodError Exception: undefined method `keys' for "production":String
(rdb:1) node[:lt_demo].to_hash  
{"port"=>8082, "domain"=>"leadtune.com", "app_env"=>"production", "branch"=>"production"}
(rdb:1) node[:lt_demo][:app_env].class
String

The bug is causing "#<Chef::Node::Attribute:0x4548dd8>" to appear in my erb templates, instead of "production" as I would expect.

Here is a screenshot of the attributes as seen in chef-server for this node:

http://screencast.com/t/MGRmNmVhNGEt

Nothing looks abnormal.