Hi, certainly demand for the CM3+ family has been very strong across all 4 memory options which has led to the product being out of stock in most locations at the moment.
There are some very healthy production quantities in the plan at the moment and just checking current lead-times tonight I see the following:
RS Components 31 May (I cant see a lead time on Allied Electronics in the US but should be similar) - RS item 182-9890
Farnell 24 June - Farnell item 2989461
Newark 23 Sept (as you correctly reported!) - Newark item 94AC6633
I think you will see similar lead times on the other memory densities at the moment
Yes, very difficult (impossible) to buy CM 3+L/8/16/32 (all memory config options) .. I was lucky, and 1 month ago I received 1 CM3+ 32G and 1 3+ Lite module out of 10 ordered. Farnell (it) reported me to wait until September 2019..