As development ramps up for the release of eosio, quick changes are being made that might effect your contracts.
One issue I have encountered in the in the dawn4.1 release, is that the type "account_name" seems to have gone obsolete and was replaced by simply "name". However, the abi generator doesn't know about this yet, and will automatically parse "account_name" as a "uint64" when it should be parsed as "name". For example your abi file might have its types defined as this:
"types": [{ "new_type_name": "account_name", "type": "uint64" } ]
when it should be:
"types": [{ "new_type_name": "account_name", "type": "name" } ]
For now you can just manual change the type from uint64 to name before deploying
This has been reported on github here: https://github.com/EOSIO/eos/issues/3227