1.5.0.2? They're getting just a little carried away with their versioning!
Ya, it would seem so. It actually makes a little bit of sense if you know what the parts mean.
The 1.5 is a major version number. Extensions and Themes aren't guaranteed to function exactly alike between major versions.
The 0 is a minor version number. The Firefox team doesn't guarantee extension and theme compatability, but make every effort not to change any APIs in such a way that they would break.
The final ".2" indicates this is a stability/bugfix/security release. It shouldn't adversely affect any themes, extensions, or plugins.
There has been a bit of grumbling about the way they are doing versioning these days. It doesn't bother me any.