Thanks for the replies. I was reading the weekly sales at dnjournal, and noticed this comment (about 3-letter domain names, but it seems like it is spilling over to 4-letter domain names now)
A lot of this week's 3-letter domains included letters like J, K, Q, W, X and Z that were once regarded by many as less letters because fewer English words begin with them than most other letters in the alphabet (thus limiting the number of potential buyers for an acronym containing those letters). However, with China emerging as one of the top (if not the top) market for short .com domains that is changing rapidly as words (and place names) with these letters are widely used and very popular there.
I noticed when I filtered my 4-letter domain names to remove (a, e, i ,o ,u, v), all of my remaining names were filled with the letters like J, K, Q, W, X, Z. And the WHOIS searches (people checking the WHOIS on my names) seems to be growing on a daily basis
Also, have received random emails (from what looks to be from China) with offers to buy these types of domain names for $150 - $200 (the offers look legit vs. all the spam emails I usually get).