nope. i always take two viewpoints on it. 1. he/she is probably backlogged like a mofo. 2. i just wasnt able to make the cut (i move on, but still give a subliminal thanks to them at least offering me the opportunity to submit.)
If I receive a submission confirmation message, I tend to leave it at that. many times notifications are shut off during special promotions, new directory announcements, etc. If I didn't make the cut, no problem - I accept their decision, after all it is their directory. There are too many opportunities to worry about a few. Unless it's an exceptional directory I'm not too concerned about the lack of communication.
Alot of directories don't send any emails regardless of if you made it in or not. There can be several reasons for this (ie. new directory, directory owner hasn't enabled the email function and so on...), so I never worry about it.
I submit to a bunch of directories and usually make it onto most of them, but if I don't hear back from certain directory I don't really care, I just used directories to get indexed faster.
Taking an0n's first point into consideration, it might be wise to revisit any directories you lucked out on, a decent timeframe after the fact (i would suggest anywhere from 3 months onwards depending on a particular directory's acceptance speed). Your best bet is to just flag all the ones that you aren't sure about and then return after the suggested timeframe, search if you have been added, if you aren't listed go for another submit.
Keep a spreadsheet of the ones you submitted to and move on to the next one. You shouldn't get worked up on particular submission unless it was dmoz or you paid to be listed. Some directories take forever to approve, so let them take their time. That still leaves you with a few thousand options to submit to.
I don't care IF the directory is new, low pr, and low traffic. But I'll email the webmaster if I believe i'll get more traffic and higher pr with them.
I like this attitude. I tend to think that 6 months is a good time period before thinking about resubmitting. A few directories have longer queues than that, but this sort of time will do for the majority. 6 months is also ample time to make improvements on a site. If you didn't make the cut, for a lot of sites this is could be thanks to inadequate content or poor design. So if you've improved on a site in the meantime it's probably worth another shot at submission.