At some point during the last decade the the word 'humbled' replaced 'proud' when expressing these sentiments. That was probably driven by people being a bunch of jerks who jump on anything they perceive as someone 'getting ahead of themselves'. So, if a young bloke says 'I'm so proud to have been selected' he'd probably cop stuff like 'why are you proud, you haven't done anything yet'.
So they are told to go with humbled, because everyone loves humility, right? Humility doesn't come before a fall.
It's annoying, but if people weren't always so critical these days, there'd be be fewer communications people paid to suck the meaning out of language.