I bought a second hand Tamron 18-270mm F/3.5-6.3 Di II VC PZD

Is it normal for this large range zoom lens to slide a bit? Like if I have it almost fully extended in zoom and point upwards, the lens slides back in on it's weight.
This is also a slightly noisier lens than I'm used to and wondering if anyone else with this lens can attest to this noise being normal.

Thanks!