Visa not checked at UK border

Hey everybody! Just flew to the UK with my HPI visa in my passport from USA. I flew through Dublin and went through customs there, I showed the visa to the guy but he didn’t care (obviously, I was in Ireland) and said they would check it later. I then flew from Dublin to Birmingham airport and there was no customs leaving my gate at any point. So my visa wasn’t checked. I’m not sure if this is necessary, is it? Does it need to be “activated”? Haha really not sure. Obviously will be retrieving my BRP soon, so they’ll know I’m here. Thanks guys! Let me know!