I've kinda figured out that's in the best interest of local fly shops to tell you that things are hopping thereabouts. Sadly, I spent too many road miles over the years chasing after some hatch that was supposedly "on" according to the local shop. A lot of that intell is often garnered second hand from customers who stopped in for supplies, often from people who couldn't tell a green drake from a green stonefly.
I remember reading a Pennsylvania hatches manual notation about the "incredible" Coffin fly hatch on a river I lived on at the time. But I don't remember more than a few over the 10 seasons I lived there. Wonderful Sulphur and March Browns, but very few Drakes.
I hope those grannoms are coming off for you but don't be surprised if they're not.