I don't know how anyone can put on 7-9lbs of actual lean muscle mass in a season. How long are we talking about, 3 months? 6 months? Even your best gainers will only put on about 1-2lbs a month of lean muscle mass. It could be that lifting will cause someone to eat more, thus adding body fat along with a little muscle. Simply looking at body weight isn't a good measurement. You have to look at lean body mass...ie: take your body fat %.
A lot of people will say they gain too much weight when lifting when in actuality they aren't testing themselves correctly (aren't taking their body fat to determine lean body mass) and are only going from "looks", which can be deceiving. I see this in female clients all the time. They'll look all swelled up after a strength training session and think they are getting bigger when it is just the acute reaction caused by lifting weights (ie: you get all "swold up")....then we weigh them and they have actually dropped weight not added.
In a nutshell: You won't get remarkably bigger from lifting if you are running a lot. You also can't judge from one season.
http://www.nytimes.com/2008/02/28/health/nutrition/28BEST.html?_r=1&oref=slogin