hydraulic floor jack goes down over time
 

hi..so i just bought this hydraulic floor jack. its one of those jacks that you tighten this knob and then pump it up and then when you want to lower it you loosen the knob and it comes down. well just recently i've noticed that it will jack up just fine (maybe takes a few too many pumpings before it lifts the car) but it does the job. the problem is that if i let it sit for a while it will slowly start going down.

is this bad? should i take it back?

I got the same jack that you're talking about, from Autozone. Mines does the same as well a few weeks after I brought it. I believe it's used just to jack the car up so you can put floor stands in it's place...not to hold up the car for whatever amount of time.
I mean...I don't know if your floor jack has wheels or not but mines does...I wouldn't want something with wheels holding up my car while I'm under it.

Return it and get another one.