That's probably it because I bought my Express brand new almost one year from now.
Ya, my newly acquired Express is "new" (well, unused, in original packaging, but with the dead sound capacitor issue, so I'm guessing an old warranty return) and I noticed the D-pad was pretty stiff, but I figured it was probably just because it was new... Well, that and sitting unused for 17 years in a box...
Some great game suggestions for portable play... I've been playing quite a bit of Splatterhouse myself, and will probably spend some time with Bonk's Adventure this weekend if I can steal a few minutes for myself... I remember trying Military Madness back on the TE back in the good ol' days, but I wasn't that enamored of it as a portable game, for some reason, though I absolutely loved it on the TG16 - bought a Gameboy Advance for myself just to play Advance Wars when it was released, simply because it reminded me so much of Military Madness