The way you are descibing it, sounds like it has come loose. I don't think this will come upder preventative maint, but maybe, the tube should be safety wired so it will not come loose. if the case is the safwty wire is broke, the tube will want to unscrew, and will do the same as you described when taking the dip stick out.
Any how, pull your top cowling, maybe your bottom also, and check the tube, maybe unscrew and inspect? I suspect it is just loose and need to be secured and saftied. Good luck.
