Yeah, I watched his first match back in TNA a year ago and a recent match and he's put on a lil weight.
But if you go back to 2006 I think Austin was even bigger then then he is now, most the X Division guys were. Chris Sabin in particular looks completely different going back to 04-05. Alex Shelley was also bigger and his mannerisms were different which I found odd(I found Shelley's mannerisms/wrestling style recently to be awkward and was surprised he didn't always wrestle/move like that.)
Anyway, Austin's weight could be a number of anythings. Aging, new lifestyle now that he is no longer on the indy scene, etc Also could be the roids.