"But it sometimes takes me a while to spot it."
It's pretty normal for grass fields to not be spotted until one is on long final.
Occassionally tarmac ones, too. Recently I approached a well known tarmac GA airfield (~800m runway) with 3 passengers, all PPLs, and I knew where it was a) because the GPS told me and b) because I've been there before many times. None of the 3 spotted it until about 2nm. Vis was about 7000m in haze and that was about when I could see the runway myself.
Very few people admit to this. I happily do, I am sorry to say
