So pretty much what topic says. While trying to upload a package I get the following error:

However, when I check test coverage anywhere else, it shows me 77%.
Developer console:

Setup --> Develop --> Apex Classes:

And Sublime Text with MavensMate:

I've seen this question as well, but the problem is that I did include all classes into my package, so all test classes are in this package as well.
Also, while I was testing I raised overall coverage by about 10%(from 50% to 60% I think), then added that class into the package, but package coverage only went up by about 2%. And going from 60% to 77% gave me about 4-5% of test coverage according to the package uploader.
Am I missing something? As I mentioned previously, all classes and triggers are in the package. Or is it just some bug that I should report to Salesforce?
for update? If you put aSystem.assert(false, 'Boom');at the end of a test case does it fail as expected in the package uploader. Or put the assertions in the code that should be covered but doesn't appear to be. – Daniel Ballinger Dec 19 '14 at 09:21System.assert(false, 'Boom');does make upload to fail. Message is One or more Apex tests failed. Resolve the test failures, then upload again., so pretty much as expected I guess. Could you please explain a bit more the running in parallel part please? – Novarg Dec 19 '14 at 13:19