Well, we'll see if more people has similar configurations of server like I do. At least I now know that I could "patch" it with Monit and have more or less workable webserver.
After I installed 1.0.4 it seems that this bug is also solved.
Apache works for more than 2 days without problems. Of course, I'll wait for a few more days before I'll be certain that there's no problem with webserver and vBNotifications.