Titanium's custom TiResponseCache.java class currently caches all HTTP responses and ignores the HTTP method. Meaning that it'll cache "POST", "PUT", "DELET", etc. which is a problem when using REST web APIs.
It should be changed to only cache HTTP "GET" responses.
(Note: iOS does not cache "HEAD" responses.)
The above is only an issue for app's which do HTTP requests natively in Java, such as via a 3rd party native library.