Condensation on cold air intake
No, this should not be happening &amp; anything rusting out your system anywhere is a significant problem. Mine was installed, right, 6-years ago &amp; I don't have any such thing. It could simply be colder outdoor air flooding that pipe or the space that the pipe runs in due to the exterior not being sealed shut to the outdoors. You may notice a cold section of floor above this pipe's area.

My other problem with your picture is that the pipe was dramatically enlarged &amp; is not the smaller diameter which connects to the rusted gray collar. This should not be &amp; is not helping matters nor is it allowing the system to run optimally &amp; may very well be a violation of the Manufacturer's installation instructions.

Call or Email the Builder &amp; put in a Warranty Claim. If the Builder doesn't respond immediately or timely. Then definitely, get an HVAC guy or firm out to inspect your system as well as this singular item's situation &amp; correct whatever needs correcting. Then, ship a copy of the bill off to the Builder for immediate reimbursement.