No idea if it’s mandatory or not, but alerting ATC to the potential problem is certainly not going to hurt.
If there’s leeway in the system then they may make you sweat less (although, as stated, there’s no requirement to - certainly in UK).
I know “communicate” comes way down on the list in an emergency but it could assist if crews communicated with ATC before it gets to that situation.
As such I’d recommend, even if it’s not mandatory in your SOPs, that you highlight the issue (with the appropriate phraseology) to ATC so that everyone knows the situation.
Who knows, maybe another crew has decided to remain silent even though they are in the same situation? It may prompt them to pipe up and hence provide a “bigger picture” to ATC.
Safety is what we’re all about, expedition too. But safety is paramount.