I've been known to have this issue with VG. At one time I was vaping 85% pg/ 15% vg over time I'm now able to handle 65% pg and 35% vg without no problems though my issue were more distracting then a little gas.
Nicotine consumption affects the muscles in your digestive tract, so it may be that your body is just adjusting to a different amount of nicotine consumption.
Actually I joined 6 years ago when I started vaping, but then went back to analogs when the old hardware wasn't cutting it. There have been a lot of advancements in 6 years, so when I tried vaping again back in September of 2014 it stuck this time.
-Treeburner
Getting a bit gassy from vaping has been my body's cue to step down my nic levels. Stepping down has never resulted in any nic cravings which makes me wonder a whole lot if nicotine without the additional chemicals from cigarettes is nearly anywhere as addictive as vaping's opponents would like us to believe.