Leaves falling off when tree is slightly shaken? the leaves are not dried out and curling on the edges, leaves are a tad bit on the pale green side, are the leaves dropping cause the soil is staying wet to long?
Could be any of these...too wet, too dry, insects, etc. Whichever it is, it is a sign of an unhealthy tree, do something to find out the problem and fix it fast.
With the ten plus inches of rain we have gotten around here this month it's no wonder.
What does the soil look like?
Has it been put out in full sun recently from somewhere shadier?
Didn't get hit by the half assed twister the other day did it? I know it was just Lapis and his toys.
we have a club in the springfield area if you are interested.