I think it's merely a smug line using Mycroft's/Gatiss's dry sense of humour frankly. It also uses words that one would expect to see on an automated machine's screen.
At this stage, there's not much of a relationship between these two characters. There never has been even in the canon. It's really not necessary and actually works more to Holmes's benefit that these two characters are 'distant' with each other.

Davina wrote:

Well he did lose his patience with the automated checkout at the supermarket.

True. In fact perhaps we should look into John's relationships with machines? He has more interaction with them than Mycroft, lol.

besleybean wrote:

Trouble is I'm never 100% sure when Mycroft is pretending...
Guess we'll know more next season.

Neither am I. Mark plays him beautifully and I love all his scenes, but I'm never sure he's being totally honest,one way or the other. His words always seem to have double meanings, even when seen in repeated viewing. I guess we will know more next season. One more point of anticipation. 

Swanpride wrote:

"What the hell happened to "Sorry for you inconvience"?

I love the interaction between Mycroft and John, it's my favourite part of the show. Especially when Mycroft tries to impress John and fails.

Their politely strained dialogue is a real highlight for me.

And I can tell you from experience on the apologies front. I have often wanted to say this ('sorry', I mean) to people when I worked in public facing jobs whilst at university. The workers are forced to say 'thank you for your patience' and get given earache (or even veiled threats of getting sacked) if they say 'sorry for the inconvenience.' The reason for this is because the second phrase implicates the speaker as being liable. If they are speaking as the employee of a company then the company is implied to be liable. If what that person is complaining about is lawsuit-worthy then this is a huge own goal and can work against them in court, especially if there is recorded evidence.

I handed in my notice and never looked back.

Swanpride wrote:

I can imagine that in the US, where you even have to warn people that coffee might be hot to avod being liable, but I'm living in Germany, where it is nearly impossible to get any kind of compensation, even if you are entitelt to one (never mind that the law works a little bit different here), and they are using the same damn signs. (Plus, I have worked the telephone myself in the past, and I never encountered the rule...in fact, it's one of the first thing I learned in seminars about communications that you don't weaken your position by saying sorry, quite the opposite, because it is the good way to break down the defences of the people you are dealing with).

I can't help but wonder if people have changed or corporations have changed? Or have corporations changed because people have changed? Because it wasn't always like this. People knew when they were being given a hard time and those who were giving it apologized for their actions. That apology made you feel better and calmer and you didn't give them attitude and they didn't give you attitude. People said please and thank you and I'm sorry and the world was better for it.