That happens, we're all human :) But as stated earlier, workload, higher priority tasks and a various other things could spark the "standby". And as written, there are a number of ways to "remember" who wanted to talk to you, like tilting a strip.

The thing that usually bugs me the most, is when you tell someone to standby, and they spill an entire position report as the "reply", and they then sound offended when you ask them to give it again, when YOU finally have the time to take it ;)

But, just take it easy out there, then we'll all be friends :)