as the left front wheel bearing gone bad i changed it following haynes instructions... but now when i drive it a while the wheelhub/brake disk is hotter than the other side (had the same with bad bearing) is this bad? or could it just be the brake disc is hot from braking? and does it hurt the grease in the bearings? should i redo all or just wait untill it brakes, can this happen withing 1000 miles? since i planned a trip i don't want it to break halfway...

 

How hot is "hot"? If it's glowing orange, that's too hot. If it's just putting off some heat, that's normal. If you packed the bearings with grease specifically rated for disk brakes, it should be OK. If you're concerned, it doesn't hurt to pull the dust cap & re-adjust the wheel bearing nut.