I occasionally just partially raise the top of my 2003 HiLo in order to crawl in and get something. If I forget to lower it again, it lowers itself within a few hours. Is this normal. (Not a problem when safety locked in full raised position.)
If everything is in top notch shape there should not be any "Creep". I believe there is a remedy for it: http://www.hilotrailerforum.com/f61/how-fix-top-half-creep-your-hilo-trailer-129/ If that doesn't correct the problem there may be leaky seals, etc. Have you checked for leaks and is the reservoir full when the top is down?