Right after the replay, BitShares encountered an exception. I relaunched it and got another:
Process: BitShares [4396]
Path: /Applications/BitShares.app/Contents/MacOS/BitShares
Identifier: org.bitshares.BitShares
Version: .. (..)
Code Type: X86-64 (Native)
Parent Process: ??? [1]
Responsible: BitShares [4396]
Date/Time: 2015-04-20 21:30:07.859 -0500
OS Version: Mac OS X 10.10.2
Report Version: 11
Crashed Thread: 0 Dispatch queue: com.apple.main-thread
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000058
VM Regions Near 0x58:
-->
__TEXT 00000001040b4000-0000000105ed6000 [ 30.1M] r-x/rwx SM=COW /Applications/BitShares.app/Contents/MacOS/BitShares
Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 org.qt-project.QtCore 0x0000000109e6fc3e QMetaObject::activate(QObject*, int, int, void**) + 62
1 org.qt-project.QtNetwork 0x0000000109b4e2cc QNetworkReply::downloadProgress(long long, long long) + 76
2 org.qt-project.QtNetwork 0x0000000109ac8770 QNetworkReplyHttpImplPrivate::replyDownloadData(QByteArray) + 1280
3 org.qt-project.QtNetwork 0x0000000109b4ead4 QNetworkReplyHttpImpl::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) + 1828
4 org.qt-project.QtCore 0x0000000109e69393 QObject::event(QEvent*) + 755
5 org.qt-project.QtWidgets 0x000000010686932b QApplicationPrivate::notify_helper(QObject*, QEvent*) + 251
6 org.qt-project.QtWidgets 0x000000010686c648 QApplication::notify(QObject*, QEvent*) + 8136
7 org.bitshares.BitShares 0x00000001040ebc6e BitSharesApp::notify(QObject*, QEvent*) + 14
8 org.qt-project.QtCore 0x0000000109e3ea5b QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) + 971
Now I launched it for the third time, no problems logging in! A fleeting bug of some sort. On to more testing...