I bought a Led Zeppelin shirt 2XL and I'll be darned if it didnt seem like a Medium when I put it on.
That REALLY just bugs the bajesus out of me when that crap happens. I have XL shirts that I have worn for years that have kept up with the changes to my body. I normally buy 2X shirts, but every so often you get a nice new 2X shirt, and one random measurement in it is small, and looks ridiculous.
I've had that problem for the past couple years in particular. I'm naturally very deep chested, but when I was in my heaviest training, my chest hit 62 inches, and I wore size 38 or 40 pants (Now, I am 58 / 42... sucks to that asthmar). The situation you described would happen ALL THE TIME. I'd pick up a shirt, and it'd fit just right, and have a nice drop, so it wouldn't look like I was an old lady blousing out a shirt. The next shirt, my shoulders would be out the end of the sleeves. Both XXLs. Ridiculous.
I feel you, brother. Especially if you found a hot zep shirt (was it the houses of the holy one?If so, I got that one too, and get yelled at for wearing it even though it's getting threadbare and has a couple of small wear holes).
As far as "goal clothes" you better believe it. I have a whole box I've been toting around since college. Hopefully I'll have trimmed enough off of my waist by the time spring rugby starts to be able to wear the pile of shorts from that box.