As others have said, trigger finger discipline and a good holster that covers the trigger guard are important.
I'd add that getting a holster that stays open for easy re-holstering is also important, as is looking at the holster when holstering to make sure there isn't anything that could catch the trigger, like a drawstring.
Don't have a Glock now, but I did have a Glock 23 and carried it both IWB and OWB without issue. If I were going to get a Glock again, I'd probably install the SCD that blues7 mentioned as an extra margin of safety, but that wouldn't eliminate the need for the measures I previously mentioned.
If you're concerned, try wearing your unloaded, but "cocked," Glock around the house for a week. Holster, un-holster, and re-holster with the aforementioned measures, and you'll probably find it's a non-issue.
Like handling any gun, paying attention to what you're doing is the key to safety.
Just my opinion.