Bees

I’m not sure this question is within your remit but I said I’d chance it. My neighbours and I have noticed an inordinate amount of small bees of late in our gardens. They often land on the wall of the house (that has been warmed by the sun) and stay there for hours making it impossible to open a window (I counted 20 bees yesterday on the wall and sills). Is this normal? No one has planted anything different in their gardens that might have attracted the bees. I’m afraid there could be nest nearby? Any advice would be welcome.