iPhoto freezes - need to worry about iPhoto library?

I was importing some pictures into iphoto last night when iphoto stopped to respond and just showed a "finishing import" or something similar message. The colorful wheel was spinning around for an hour, but nothing changed. Activity Monitor showed a "not responding", so finally I did a "Force Quit". Now, do I need to worry about the library? iphoto did start normally again, and the number of pictures (about 40k) and events it showed is within the expected range. But still... I feel a bit worried.

Is there a way to do a kind of consistency check to make sure that everything's fine... or am I overly worried?

Thanks, Mal. That's a good idea. I'll try that.

And regarding the backup: I'm just in the process of setting up my first iMac and transferring all my files. The iphoto freeze actually happened at the very end of a series of sessions of my photos from an external hard drive. So I still have all the data there, but I would like to avoid going through another 5 to 6 hours long importing procedure.

Once it's set up, I want to (1) use the external hard drive to do a time machine backup (what's the best file system for that?) and (2) use another one (which currently also holds a backup of all my data) to do an incremental backup in humanly readable form (still looking for some software for that).

It worked. It turned out that the 22 pictures (and the corresponding event) I was importing when iphoto crashed were missing in the library after the check. Everything else is still there... and somehow iphoto seems to run a bit faster after rebuilding the library...