Common. Nothing to worry about. The one with the least resistance will move first, usually the small one. Depends on temp, level, alignment of the moon,......(only kidding)
The pump just makes pressure to both slides at the same time. The slides will eventually go out and be fine.
2012 Ford F250 ext. Cab 4x4
2002 Jeep Wrangler Sahara
2008 Yamaha V-Star 650 Classic
2008 Work and Play 18LT